/*
 * Copyright (c) 2008-2015, Dave Benson and the protobuf-c authors.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*! \file
 * Support library for `protoc-c` generated code.
 *
 * This file implements the public API used by the code generated
 * by `protoc-c`.
 *
 * \authors Dave Benson and the protobuf-c authors
 *
 * \copyright 2008-2014. Licensed under the terms of the [BSD-2-Clause] license.
 */

/**
 * \todo 64-BIT OPTIMIZATION: certain implementations use 32-bit math
 * even on 64-bit platforms (uint64_size, uint64_pack, parse_uint64).
 *
 * \todo Use size_t consistently.
 */

#include <stdlib.h>	/* for malloc, free */
#include <string.h>	/* for strcmp, strlen, memcpy, memmove, memset */
#include <vmtypes.h>
#include "protobuf.h"

#ifdef PROTOBUF_DEBUG
#include <stdio.h>
#define PRINT(x) printf x
#else
#define PRINT(x)
#endif /*PROTOBUF_DEBUG*/

#define PROTOBUF_C__ASSERT_NOT_REACHED() assert(0)

/* Workaround for Microsoft compilers. */
#ifdef _MSC_VER
# define inline __inline
#endif

/**
 * \defgroup internal Internal functions and macros
 *
 * These are not exported by the library but are useful to developers working
 * on `libprotobuf-c` itself.
 */

/**
 * \defgroup macros Utility macros for manipulating structures
 *
 * Macros and constants used to manipulate the base "classes" generated by
 * `protobuf-c`. They also define limits and check correctness.
 *
 * \ingroup internal
 * @{
 */

/** The maximum length of a 64-bit integer in varint encoding. */
#define MAX_UINT64_ENCODED_SIZE		10

#ifndef PROTOBUF_C_UNPACK_ERROR
# define PROTOBUF_C_UNPACK_ERROR(...)
#endif

const char protobuf_c_empty_string[] = "";

/**
 * Internal `ProtobufCMessage` manipulation macro.
 *
 * Base macro for manipulating a `ProtobufCMessage`. Used by STRUCT_MEMBER() and
 * STRUCT_MEMBER_PTR().
 */
#define STRUCT_MEMBER_P(struct_p, struct_offset) \
    ((void *) ((uint8_t *) (struct_p) + (struct_offset)))

/**
 * Return field in a `ProtobufCMessage` based on offset.
 *
 * Take a pointer to a `ProtobufCMessage` and find the field at the offset.
 * Cast it to the passed type.
 */
#define STRUCT_MEMBER(member_type, struct_p, struct_offset) \
    (*(member_type *) STRUCT_MEMBER_P((struct_p), (struct_offset)))

/**
 * Return field in a `ProtobufCMessage` based on offset.
 *
 * Take a pointer to a `ProtobufCMessage` and find the field at the offset. Cast
 * it to a pointer to the passed type.
 */
#define STRUCT_MEMBER_PTR(member_type, struct_p, struct_offset) \
    ((member_type *) STRUCT_MEMBER_P((struct_p), (struct_offset)))

/* Assertions for magic numbers. */

#define ASSERT_IS_ENUM_DESCRIPTOR(desc) \
    assert((desc)->magic == PROTOBUF_C__ENUM_DESCRIPTOR_MAGIC)

#define ASSERT_IS_MESSAGE_DESCRIPTOR(desc) \
    assert((desc)->magic == PROTOBUF_C__MESSAGE_DESCRIPTOR_MAGIC)

#define ASSERT_IS_MESSAGE(message) \
    ASSERT_IS_MESSAGE_DESCRIPTOR((message)->descriptor)

#define ASSERT_IS_SERVICE_DESCRIPTOR(desc) \
    assert((desc)->magic == PROTOBUF_C__SERVICE_DESCRIPTOR_MAGIC)

/**@}*/

/* --- version --- */

const char *
protobuf_c_version(void)
{
    return PROTOBUF_C_VERSION;
}

uint32_t
protobuf_c_version_number(void)
{
    return PROTOBUF_C_VERSION_NUMBER;
}

/* --- allocator --- */

static void *
system_alloc(void *allocator_data, size_t size)
{
    UNUSED(allocator_data);
    void * ptr = PanicUnlessMalloc(size);
    return ptr;
}

static void
system_free(void *allocator_data, void *data)
{
    UNUSED(allocator_data);
    free(data);
}

static inline void *
do_alloc(ProtobufCAllocator *allocator, size_t size)
{
    return allocator->alloc(allocator->allocator_data, size);
}

static inline void
do_free(ProtobufCAllocator *allocator, void *data)
{
    if (data != NULL)
        allocator->free(allocator->allocator_data, data);
}

/*
 * This allocator uses the system's malloc() and free(). It is the default
 * allocator used if NULL is passed as the ProtobufCAllocator to an exported
 * function.
 */
static ProtobufCAllocator protobuf_c__allocator = {
    .alloc = &system_alloc,
    .free = &system_free,
    .allocator_data = NULL,
};

/* === buffer-simple === */

void
protobuf_c_buffer_simple_append(ProtobufCBuffer *buffer,
                size_t len, const uint8_t *data)
{
    ProtobufCBufferSimple *simp = (ProtobufCBufferSimple *) buffer;
    size_t new_len = simp->len + len;

    if (new_len > simp->alloced) {
        ProtobufCAllocator *allocator = simp->allocator;
        size_t new_alloced = simp->alloced * 2;
        uint8_t *new_data;

        if (allocator == NULL)
            allocator = &protobuf_c__allocator;
        while (new_alloced < new_len)
            new_alloced += new_alloced;
        new_data = do_alloc(allocator, new_alloced);
        if (!new_data)
            return;
        memcpy(new_data, simp->data, simp->len);
        if (simp->must_free_data)
            do_free(allocator, simp->data);
        else
            simp->must_free_data = TRUE;
        simp->data = new_data;
        simp->alloced = new_alloced;
    }
    memcpy(simp->data + simp->len, data, len);
    simp->len = new_len;
}

/**
 * \defgroup packedsz protobuf_c_message_get_packed_size() implementation
 *
 * Routines mainly used by protobuf_c_message_get_packed_size().
 *
 * \ingroup internal
 * @{
 */

/**
 * Return the number of bytes required to store the tag for the field. Includes
 * 3 bits for the wire-type, and a single bit that denotes the end-of-tag.
 *
 * \param number
 *      Field tag to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
get_tag_size(uint32_t number)
{
    if (number < (1UL << 4)) {
        return 1;
    } else if (number < (1UL << 11)) {
        return 2;
    } else if (number < (1UL << 18)) {
        return 3;
    } else if (number < (1UL << 25)) {
        return 4;
    } else {
        return 5;
    }
}

/**
 * Return the number of bytes required to store a variable-length unsigned
 * 32-bit integer in base-128 varint encoding.
 *
 * \param v
 *      Value to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
uint32_size(uint32_t v)
{
    if (v < (1UL << 7)) {
        return 1;
    } else if (v < (1UL << 14)) {
        return 2;
    } else if (v < (1UL << 21)) {
        return 3;
    } else if (v < (1UL << 28)) {
        return 4;
    } else {
        return 5;
    }
}

/**
 * Return the number of bytes required to store a variable-length signed 32-bit
 * integer in base-128 varint encoding.
 *
 * \param v
 *      Value to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
int32_size(int32_t v)
{
    if (v < 0) {
        return 10;
    } else if (v < (1L << 7)) {
        return 1;
    } else if (v < (1L << 14)) {
        return 2;
    } else if (v < (1L << 21)) {
        return 3;
    } else if (v < (1L << 28)) {
        return 4;
    } else {
        return 5;
    }
}

/**
 * Return the ZigZag-encoded 32-bit unsigned integer form of a 32-bit signed
 * integer.
 *
 * \param v
 *      Value to encode.
 * \return
 *      ZigZag encoded integer.
 */
static inline uint32_t
zigzag32(int32_t v)
{
    if (v < 0)
        return (-(uint32_t)v) * 2 - 1;
    else
        return (uint32_t)(v) * 2;
}

/**
 * Return the number of bytes required to store a signed 32-bit integer,
 * converted to an unsigned 32-bit integer with ZigZag encoding, using base-128
 * varint encoding.
 *
 * \param v
 *      Value to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
sint32_size(int32_t v)
{
    return uint32_size(zigzag32(v));
}

/**
 * Return the number of bytes required to store a 64-bit unsigned integer in
 * base-128 varint encoding.
 *
 * \param v
 *      Value to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
uint64_size(_uint64_t v)
{
    uint32_t upper_v = (uint32_t) (v >> 32);

    if (upper_v == 0) {
        return uint32_size((uint32_t) v);
    } else if (upper_v < (1UL << 3)) {
        return 5;
    } else if (upper_v < (1UL << 10)) {
        return 6;
    } else if (upper_v < (1UL << 17)) {
        return 7;
    } else if (upper_v < (1UL << 24)) {
        return 8;
    } else if (upper_v < (1UL << 31)) {
        return 9;
    } else {
        return 10;
    }
}

/**
 * Return the ZigZag-encoded 64-bit unsigned integer form of a 64-bit signed
 * integer.
 *
 * \param v
 *      Value to encode.
 * \return
 *      ZigZag encoded integer.
 */
static inline _uint64_t
zigzag64(_int64_t v)
{
    if (v < 0)
        return (-(_uint64_t)v) * 2 - 1;
    else
        return (_uint64_t)(v) * 2;
}

/**
 * Return the number of bytes required to store a signed 64-bit integer,
 * converted to an unsigned 64-bit integer with ZigZag encoding, using base-128
 * varint encoding.
 *
 * \param v
 *      Value to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
sint64_size(_int64_t v)
{
    return uint64_size(zigzag64(v));
}

/**
 * Calculate the serialized size of a single required message field, including
 * the space needed by the preceding tag.
 *
 * \param field
 *      Field descriptor for member.
 * \param member
 *      Field to encode.
 * \return
 *      Number of bytes required.
 */
static size_t
required_field_get_packed_size(const ProtobufCFieldDescriptor *field,
                   const void *member)
{
    size_t rv = get_tag_size(field->id);

    switch (field->type) {
    case PROTOBUF_C_TYPE_SINT32:
        return rv + sint32_size(*(const int32_t *) member);
    case PROTOBUF_C_TYPE_ENUM:
    case PROTOBUF_C_TYPE_INT32:
        return rv + int32_size(*(const int32_t *) member);
    case PROTOBUF_C_TYPE_UINT32:
        return rv + uint32_size(*(const uint32_t *) member);
    case PROTOBUF_C_TYPE_SINT64:
        return rv + sint64_size(*(const _int64_t *) member);
    case PROTOBUF_C_TYPE_INT64:
    case PROTOBUF_C_TYPE_UINT64:
        return rv + uint64_size(*(const _uint64_t *) member);
    case PROTOBUF_C_TYPE_SFIXED32:
    case PROTOBUF_C_TYPE_FIXED32:
        return rv + 4;
    case PROTOBUF_C_TYPE_SFIXED64:
    case PROTOBUF_C_TYPE_FIXED64:
        return rv + 8;
    case PROTOBUF_C_TYPE_BOOL:
        return rv + 1;
    case PROTOBUF_C_TYPE_FLOAT:
        return rv + 4;
    case PROTOBUF_C_TYPE_DOUBLE:
        return rv + 8;
    case PROTOBUF_C_TYPE_STRING: {
        const char *str = *(char * const *) member;
        size_t len = str ? strlen(str) : 0;
        return rv + uint32_size(len) + len;
    }
    case PROTOBUF_C_TYPE_BYTES: {
        size_t len = ((const ProtobufCBinaryData *) member)->len;
        return rv + uint32_size(len) + len;
    }
    case PROTOBUF_C_TYPE_MESSAGE: {
        const ProtobufCMessage *msg = *(ProtobufCMessage * const *) member;
        size_t subrv = msg ? protobuf_c_message_get_packed_size(msg) : 0;
        return rv + uint32_size(subrv) + subrv;
    }
    }
    PROTOBUF_C__ASSERT_NOT_REACHED();
    return 0;
}

/**
 * Calculate the serialized size of a single oneof message field, including
 * the space needed by the preceding tag. Returns 0 if the oneof field isn't
 * selected or is not set.
 *
 * \param field
 *      Field descriptor for member.
 * \param oneof_case
 *      Enum value that selects the field in the oneof.
 * \param member
 *      Field to encode.
 * \return
 *      Number of bytes required.
 */
static size_t
oneof_field_get_packed_size(const ProtobufCFieldDescriptor *field,
                uint32_t oneof_case,
                const void *member)
{
    if (oneof_case != field->id) {
        return 0;
    }
    if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
        field->type == PROTOBUF_C_TYPE_STRING)
    {
        const void *ptr = *(const void * const *) member;
        if (ptr == NULL || ptr == field->default_value)
            return 0;
    }
    return required_field_get_packed_size(field, member);
}

/**
 * Calculate the serialized size of a single optional message field, including
 * the space needed by the preceding tag. Returns 0 if the optional field isn't
 * set.
 *
 * \param field
 *      Field descriptor for member.
 * \param has
 *      True if the field exists, false if not.
 * \param member
 *      Field to encode.
 * \return
 *      Number of bytes required.
 */
static size_t
optional_field_get_packed_size(const ProtobufCFieldDescriptor *field,
                   const protobuf_c_boolean has,
                   const void *member)
{
    if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
        field->type == PROTOBUF_C_TYPE_STRING)
    {
        const void *ptr = *(const void * const *) member;
        if (ptr == NULL || ptr == field->default_value)
            return 0;
    } else {
        if (!has)
            return 0;
    }
    return required_field_get_packed_size(field, member);
}

static protobuf_c_boolean
field_is_zeroish(const ProtobufCFieldDescriptor *field,
         const void *member)
{
    protobuf_c_boolean ret = FALSE;

    switch (field->type) {
    case PROTOBUF_C_TYPE_BOOL:
        ret = (0 == *(const protobuf_c_boolean *) member);
        break;
    case PROTOBUF_C_TYPE_ENUM:
    case PROTOBUF_C_TYPE_SINT32:
    case PROTOBUF_C_TYPE_INT32:
    case PROTOBUF_C_TYPE_UINT32:
    case PROTOBUF_C_TYPE_SFIXED32:
    case PROTOBUF_C_TYPE_FIXED32:
        ret = (0 == *(const uint32_t *) member);
        break;
    case PROTOBUF_C_TYPE_SINT64:
    case PROTOBUF_C_TYPE_INT64:
    case PROTOBUF_C_TYPE_UINT64:
    case PROTOBUF_C_TYPE_SFIXED64:
    case PROTOBUF_C_TYPE_FIXED64:
        ret = (0 == *(const _uint64_t *) member);
        break;
    case PROTOBUF_C_TYPE_FLOAT:
        ret = (0 == *(const float *) member);
        break;
    case PROTOBUF_C_TYPE_DOUBLE:
        ret = (0 == *(const double *) member);
        break;
    case PROTOBUF_C_TYPE_STRING:
        ret = (NULL == *(const char * const *) member) ||
              ('\0' == **(const char * const *) member);
        break;
    case PROTOBUF_C_TYPE_BYTES:
    case PROTOBUF_C_TYPE_MESSAGE:
        ret = (NULL == *(const void * const *) member);
        break;
    default:
        ret = TRUE;
        break;
    }

    return ret;
}

/**
 * Calculate the serialized size of a single unlabeled message field, including
 * the space needed by the preceding tag. Returns 0 if the field isn't set or
 * if it is set to a "zeroish" value (null pointer or 0 for numerical values).
 * Unlabeled fields are supported only in proto3.
 *
 * \param field
 *      Field descriptor for member.
 * \param member
 *      Field to encode.
 * \return
 *      Number of bytes required.
 */
static size_t
unlabeled_field_get_packed_size(const ProtobufCFieldDescriptor *field,
                const void *member)
{
    if (field_is_zeroish(field, member))
        return 0;
    return required_field_get_packed_size(field, member);
}

/**
 * Calculate the serialized size of repeated message fields, which may consist
 * of any number of values (including 0). Includes the space needed by the
 * preceding tags (as needed).
 *
 * \param field
 *      Field descriptor for member.
 * \param count
 *      Number of repeated field members.
 * \param member
 *      Field to encode.
 * \return
 *      Number of bytes required.
 */
static size_t
repeated_field_get_packed_size(const ProtobufCFieldDescriptor *field,
                   size_t count, const void *member)
{
    size_t header_size;
    size_t rv = 0;
    unsigned i;
    void *array = *(void * const *) member;

    if (count == 0)
        return 0;
    header_size = get_tag_size(field->id);
    if (0 == (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED))
        header_size *= count;

    switch (field->type) {
    case PROTOBUF_C_TYPE_SINT32:
        for (i = 0; i < count; i++)
            rv += sint32_size(((int32_t *) array)[i]);
        break;
    case PROTOBUF_C_TYPE_ENUM:
    case PROTOBUF_C_TYPE_INT32:
        for (i = 0; i < count; i++)
            rv += int32_size(((int32_t *) array)[i]);
        break;
    case PROTOBUF_C_TYPE_UINT32:
        for (i = 0; i < count; i++)
            rv += uint32_size(((uint32_t *) array)[i]);
        break;
    case PROTOBUF_C_TYPE_SINT64:
        for (i = 0; i < count; i++)
            rv += sint64_size(((_int64_t *) array)[i]);
        break;
    case PROTOBUF_C_TYPE_INT64:
    case PROTOBUF_C_TYPE_UINT64:
        for (i = 0; i < count; i++)
            rv += uint64_size(((_uint64_t *) array)[i]);
        break;
    case PROTOBUF_C_TYPE_SFIXED32:
    case PROTOBUF_C_TYPE_FIXED32:
    case PROTOBUF_C_TYPE_FLOAT:
        rv += 4 * count;
        break;
    case PROTOBUF_C_TYPE_SFIXED64:
    case PROTOBUF_C_TYPE_FIXED64:
    case PROTOBUF_C_TYPE_DOUBLE:
        rv += 8 * count;
        break;
    case PROTOBUF_C_TYPE_BOOL:
        rv += count;
        break;
    case PROTOBUF_C_TYPE_STRING:
        for (i = 0; i < count; i++) {
            size_t len = strlen(((char **) array)[i]);
            rv += uint32_size(len) + len;
        }
        break;
    case PROTOBUF_C_TYPE_BYTES:
        for (i = 0; i < count; i++) {
            size_t len = ((ProtobufCBinaryData *) array)[i].len;
            rv += uint32_size(len) + len;
        }
        break;
    case PROTOBUF_C_TYPE_MESSAGE:
        for (i = 0; i < count; i++) {
            size_t len = protobuf_c_message_get_packed_size(
                ((ProtobufCMessage **) array)[i]);
            rv += uint32_size(len) + len;
        }
        break;
    }

    if (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED))
        header_size += uint32_size(rv);
    return header_size + rv;
}

/**
 * Calculate the serialized size of an unknown field, i.e. one that is passed
 * through mostly uninterpreted. This is required for forward compatibility if
 * new fields are added to the message descriptor.
 *
 * \param field
 *      Unknown field type.
 * \return
 *      Number of bytes required.
 */
static inline size_t
unknown_field_get_packed_size(const ProtobufCMessageUnknownField *field)
{
    return get_tag_size(field->tag) + field->len;
}

/**@}*/

/*
 * Calculate the serialized size of the message.
 */
size_t protobuf_c_message_get_packed_size(const ProtobufCMessage *message)
{
    unsigned i;
    size_t rv = 0;

    ASSERT_IS_MESSAGE(message);
    for (i = 0; i < message->descriptor->n_fields; i++) {
        const ProtobufCFieldDescriptor *field =
            message->descriptor->fields + i;
        const void *member =
            ((const char *) message) + field->offset;
        const void *qmember =
            ((const char *) message) + field->quantifier_offset;

        if (field->label == PROTOBUF_C_LABEL_REQUIRED) {
            rv += required_field_get_packed_size(field, member);
        } else if ((field->label == PROTOBUF_C_LABEL_OPTIONAL ||
                field->label == PROTOBUF_C_LABEL_NONE) &&
               (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_ONEOF))) {
            rv += oneof_field_get_packed_size(
                field,
                *(const uint32_t *) qmember,
                member
            );
        } else if (field->label == PROTOBUF_C_LABEL_OPTIONAL) {
            rv += optional_field_get_packed_size(
                field,
                *(protobuf_c_boolean *) qmember,
                member
            );
        } else if (field->label == PROTOBUF_C_LABEL_NONE) {
            rv += unlabeled_field_get_packed_size(
                field,
                member
            );
        } else {
            rv += repeated_field_get_packed_size(
                field,
                *(const size_t *) qmember,
                member
            );
        }
    }
    for (i = 0; i < message->n_unknown_fields; i++)
        rv += unknown_field_get_packed_size(&message->unknown_fields[i]);
    return rv;
}

/**
 * \defgroup pack protobuf_c_message_pack() implementation
 *
 * Routines mainly used by protobuf_c_message_pack().
 *
 * \ingroup internal
 * @{
 */

/**
 * Pack an unsigned 32-bit integer in base-128 varint encoding and return the
 * number of bytes written, which must be 5 or less.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
uint32_pack(uint32_t value, uint8_t *out)
{
    unsigned rv = 0;

    if (value >= 0x80) {
        out[rv++] = value | 0x80;
        value >>= 7;
        if (value >= 0x80) {
            out[rv++] = value | 0x80;
            value >>= 7;
            if (value >= 0x80) {
                out[rv++] = value | 0x80;
                value >>= 7;
                if (value >= 0x80) {
                    out[rv++] = value | 0x80;
                    value >>= 7;
                }
            }
        }
    }
    /* assert: value<128 */
    out[rv++] = value;
    return rv;
}

/**
 * Pack a signed 32-bit integer and return the number of bytes written.
 * Negative numbers are encoded as two's complement 64-bit integers.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
int32_pack(int32_t value, uint8_t *out)
{
    if (value < 0) {
        out[0] = value | 0x80;
        out[1] = (value >> 7) | 0x80;
        out[2] = (value >> 14) | 0x80;
        out[3] = (value >> 21) | 0x80;
        out[4] = (value >> 28) | 0x80;
        out[5] = out[6] = out[7] = out[8] = 0xff;
        out[9] = 0x01;
        return 10;
    } else {
        return uint32_pack(value, out);
    }
}

/**
 * Pack a signed 32-bit integer using ZigZag encoding and return the number of
 * bytes written.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
sint32_pack(int32_t value, uint8_t *out)
{
    return uint32_pack(zigzag32(value), out);
}

/**
 * Pack a 64-bit unsigned integer using base-128 varint encoding and return the
 * number of bytes written.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
uint64_pack(_uint64_t value, uint8_t *out)
{
    uint32_t hi = (uint32_t) (value >> 32);
    uint32_t lo = (uint32_t) value;
    unsigned rv;

    if (hi == 0)
        return uint32_pack((uint32_t) lo, out);
    out[0] = (lo) | 0x80;
    out[1] = (lo >> 7) | 0x80;
    out[2] = (lo >> 14) | 0x80;
    out[3] = (lo >> 21) | 0x80;
    if (hi < 8) {
        out[4] = (hi << 4) | (lo >> 28);
        return 5;
    } else {
        out[4] = ((hi & 7) << 4) | (lo >> 28) | 0x80;
        hi >>= 3;
    }
    rv = 5;
    while (hi >= 128) {
        out[rv++] = hi | 0x80;
        hi >>= 7;
    }
    out[rv++] = hi;
    return rv;
}

/**
 * Pack a 64-bit signed integer in ZigZag encoding and return the number of
 * bytes written.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
sint64_pack(_int64_t value, uint8_t *out)
{
    return uint64_pack(zigzag64(value), out);
}

/**
 * Pack a 32-bit quantity in little-endian byte order. Used for protobuf wire
 * types fixed32, sfixed32, float. Similar to "htole32".
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
fixed32_pack(uint32_t value, void *out)
{
#if !defined(WORDS_BIGENDIAN)
    memcpy(out, &value, 4);
#else
    uint8_t *buf = out;

    buf[0] = value;
    buf[1] = value >> 8;
    buf[2] = value >> 16;
    buf[3] = value >> 24;
#endif
    return 4;
}

/**
 * Pack a 64-bit quantity in little-endian byte order. Used for protobuf wire
 * types fixed64, sfixed64, double. Similar to "htole64".
 *
 * \todo The big-endian impl is really only good for 32-bit machines, a 64-bit
 * version would be appreciated, plus a way to decide to use 64-bit math where
 * convenient.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
fixed64_pack(_uint64_t value, void *out)
{
#if !defined(WORDS_BIGENDIAN)
    memcpy(out, &value, 8);
#else
    fixed32_pack(value, out);
    fixed32_pack(value >> 32, ((char *) out) + 4);
#endif
    return 8;
}

/**
 * Pack a boolean value as an integer and return the number of bytes written.
 *
 * \todo Perhaps on some platforms *out = !!value would be a better impl, b/c
 * that is idiomatic C++ in some STL implementations.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
boolean_pack(protobuf_c_boolean value, uint8_t *out)
{
    *out = value ? TRUE : FALSE;
    return 1;
}

/**
 * Pack a NUL-terminated C string and return the number of bytes written. The
 * output includes a length delimiter.
 *
 * The NULL pointer is treated as an empty string. This isn't really necessary,
 * but it allows people to leave required strings blank. (See Issue #13 in the
 * bug tracker for a little more explanation).
 *
 * \param str
 *      String to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
string_pack(const char *str, uint8_t *out)
{
    if (str == NULL) {
        out[0] = 0;
        return 1;
    } else {
        size_t len = strlen(str);
        size_t rv = uint32_pack(len, out);
        memcpy(out + rv, str, len);
        return rv + len;
    }
}

/**
 * Pack a ProtobufCBinaryData and return the number of bytes written. The output
 * includes a length delimiter.
 *
 * \param bd
 *      ProtobufCBinaryData to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
binary_data_pack(const ProtobufCBinaryData *bd, uint8_t *out)
{
    size_t len = bd->len;
    size_t rv = uint32_pack(len, out);
    memcpy(out + rv, bd->data, len);
    return rv + len;
}

/**
 * Pack a ProtobufCMessage and return the number of bytes written. The output
 * includes a length delimiter.
 *
 * \param message
 *      ProtobufCMessage object to pack.
 * \param[out] out
 *      Packed message.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
prefixed_message_pack(const ProtobufCMessage *message, uint8_t *out)
{
    if (message == NULL) {
        out[0] = 0;
        return 1;
    } else {
        size_t rv = protobuf_c_message_pack(message, out + 1);
        uint32_t rv_packed_size = uint32_size(rv);
        if (rv_packed_size != 1)
            memmove(out + rv_packed_size, out + 1, rv);
        return uint32_pack(rv, out) + rv;
    }
}

/**
 * Pack a field tag.
 *
 * Wire-type will be added in required_field_pack().
 *
 * \todo Just call uint64_pack on 64-bit platforms.
 *
 * \param id
 *      Tag value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
tag_pack(uint32_t id, uint8_t *out)
{
    if (id < (1UL << (32 - 3)))
        return uint32_pack(id << 3, out);
    else
        return uint64_pack(((_uint64_t) id) << 3, out);
}

/**
 * Pack a required field and return the number of bytes written.
 *
 * \param field
 *      Field descriptor.
 * \param member
 *      The field member.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
required_field_pack(const ProtobufCFieldDescriptor *field,
            const void *member, uint8_t *out)
{
    size_t rv = tag_pack(field->id, out);

    switch (field->type) {
    case PROTOBUF_C_TYPE_SINT32:
        out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        return rv + sint32_pack(*(const int32_t *) member, out + rv);
    case PROTOBUF_C_TYPE_ENUM:
    case PROTOBUF_C_TYPE_INT32:
        out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        return rv + int32_pack(*(const int32_t *) member, out + rv);
    case PROTOBUF_C_TYPE_UINT32:
        out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        return rv + uint32_pack(*(const uint32_t *) member, out + rv);
    case PROTOBUF_C_TYPE_SINT64:
        out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        return rv + sint64_pack(*(const _int64_t *) member, out + rv);
    case PROTOBUF_C_TYPE_INT64:
    case PROTOBUF_C_TYPE_UINT64:
        out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        return rv + uint64_pack(*(const _uint64_t *) member, out + rv);
    case PROTOBUF_C_TYPE_SFIXED32:
    case PROTOBUF_C_TYPE_FIXED32:
    case PROTOBUF_C_TYPE_FLOAT:
        out[0] |= PROTOBUF_C_WIRE_TYPE_32BIT;
        return rv + fixed32_pack(*(const uint32_t *) member, out + rv);
    case PROTOBUF_C_TYPE_SFIXED64:
    case PROTOBUF_C_TYPE_FIXED64:
    case PROTOBUF_C_TYPE_DOUBLE:
        out[0] |= PROTOBUF_C_WIRE_TYPE_64BIT;
        return rv + fixed64_pack(*(const _uint64_t *) member, out + rv);
    case PROTOBUF_C_TYPE_BOOL:
        out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        return rv + boolean_pack(*(const protobuf_c_boolean *) member, out + rv);
    case PROTOBUF_C_TYPE_STRING:
        out[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
        return rv + string_pack(*(char *const *) member, out + rv);
    case PROTOBUF_C_TYPE_BYTES:
        out[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
        return rv + binary_data_pack((const ProtobufCBinaryData *) member, out + rv);
    case PROTOBUF_C_TYPE_MESSAGE:
        out[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
        return rv + prefixed_message_pack(*(ProtobufCMessage * const *) member, out + rv);
    }
    PROTOBUF_C__ASSERT_NOT_REACHED();
    return 0;
}

/**
 * Pack a oneof field and return the number of bytes written. Only packs the
 * field that is selected by the case enum.
 *
 * \param field
 *      Field descriptor.
 * \param oneof_case
 *      Enum value that selects the field in the oneof.
 * \param member
 *      The field member.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
oneof_field_pack(const ProtobufCFieldDescriptor *field,
         uint32_t oneof_case,
         const void *member, uint8_t *out)
{
    if (oneof_case != field->id) {
        return 0;
    }
    if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
        field->type == PROTOBUF_C_TYPE_STRING)
    {
        const void *ptr = *(const void * const *) member;
        if (ptr == NULL || ptr == field->default_value)
            return 0;
    }
    return required_field_pack(field, member, out);
}

/**
 * Pack an optional field and return the number of bytes written.
 *
 * \param field
 *      Field descriptor.
 * \param has
 *      Whether the field is set.
 * \param member
 *      The field member.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
optional_field_pack(const ProtobufCFieldDescriptor *field,
            const protobuf_c_boolean has,
            const void *member, uint8_t *out)
{
    if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
        field->type == PROTOBUF_C_TYPE_STRING)
    {
        const void *ptr = *(const void * const *) member;
        if (ptr == NULL || ptr == field->default_value)
            return 0;
    } else {
        if (!has)
            return 0;
    }
    return required_field_pack(field, member, out);
}

/**
 * Pack an unlabeled field and return the number of bytes written.
 *
 * \param field
 *      Field descriptor.
 * \param member
 *      The field member.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
unlabeled_field_pack(const ProtobufCFieldDescriptor *field,
             const void *member, uint8_t *out)
{
    if (field_is_zeroish(field, member))
        return 0;
    return required_field_pack(field, member, out);
}

/**
 * Given a field type, return the in-memory size.
 *
 * \todo Implement as a table lookup.
 *
 * \param type
 *      Field type.
 * \return
 *      Size of the field.
 */
static inline size_t
sizeof_elt_in_repeated_array(ProtobufCType type)
{
    switch (type) {
    case PROTOBUF_C_TYPE_SINT32:
    case PROTOBUF_C_TYPE_INT32:
    case PROTOBUF_C_TYPE_UINT32:
    case PROTOBUF_C_TYPE_SFIXED32:
    case PROTOBUF_C_TYPE_FIXED32:
    case PROTOBUF_C_TYPE_FLOAT:
    case PROTOBUF_C_TYPE_ENUM:
        return 4;
    case PROTOBUF_C_TYPE_SINT64:
    case PROTOBUF_C_TYPE_INT64:
    case PROTOBUF_C_TYPE_UINT64:
    case PROTOBUF_C_TYPE_SFIXED64:
    case PROTOBUF_C_TYPE_FIXED64:
    case PROTOBUF_C_TYPE_DOUBLE:
        return 8;
    case PROTOBUF_C_TYPE_BOOL:
        return sizeof(protobuf_c_boolean);
    case PROTOBUF_C_TYPE_STRING:
    case PROTOBUF_C_TYPE_MESSAGE:
        return sizeof(void *);
    case PROTOBUF_C_TYPE_BYTES:
        return sizeof(ProtobufCBinaryData);
    }
    PROTOBUF_C__ASSERT_NOT_REACHED();
    return 0;
}

/**
 * Pack an array of 32-bit quantities.
 *
 * \param[out] out
 *      Destination.
 * \param[in] in
 *      Source.
 * \param[in] n
 *      Number of elements in the source array.
 */
static void
copy_to_little_endian_32(void *out, const void *in, const unsigned n)
{
#if !defined(WORDS_BIGENDIAN)
    memcpy(out, in, n * 4);
#else
    unsigned i;
    const uint32_t *ini = in;
    for (i = 0; i < n; i++)
        fixed32_pack(ini[i], (uint32_t *) out + i);
#endif
}

/**
 * Pack an array of 64-bit quantities.
 *
 * \param[out] out
 *      Destination.
 * \param[in] in
 *      Source.
 * \param[in] n
 *      Number of elements in the source array.
 */
static void
copy_to_little_endian_64(void *out, const void *in, const unsigned n)
{
#if !defined(WORDS_BIGENDIAN)
    memcpy(out, in, n * 8);
#else
    unsigned i;
    const _uint64_t *ini = in;
    for (i = 0; i < n; i++)
        fixed64_pack(ini[i], (_uint64_t *) out + i);
#endif
}

/**
 * Get the minimum number of bytes required to pack a field value of a
 * particular type.
 *
 * \param type
 *      Field type.
 * \return
 *      Number of bytes.
 */
static unsigned
get_type_min_size(ProtobufCType type)
{
    if (type == PROTOBUF_C_TYPE_SFIXED32 ||
        type == PROTOBUF_C_TYPE_FIXED32 ||
        type == PROTOBUF_C_TYPE_FLOAT)
    {
        return 4;
    }
    if (type == PROTOBUF_C_TYPE_SFIXED64 ||
        type == PROTOBUF_C_TYPE_FIXED64 ||
        type == PROTOBUF_C_TYPE_DOUBLE)
    {
        return 8;
    }
    return 1;
}

/**
 * Packs the elements of a repeated field and returns the serialised field and
 * its length.
 *
 * \param field
 *      Field descriptor.
 * \param count
 *      Number of elements in the repeated field array.
 * \param member
 *      Pointer to the elements for this repeated field.
 * \param[out] out
 *      Serialised representation of the repeated field.
 * \return
 *      Number of bytes serialised to `out`.
 */
static size_t
repeated_field_pack(const ProtobufCFieldDescriptor *field,
            size_t count, const void *member, uint8_t *out)
{
    void *array = *(void * const *) member;
    unsigned i;

    if (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED)) {
        unsigned header_len;
        unsigned len_start;
        unsigned min_length;
        unsigned payload_len;
        unsigned length_size_min;
        unsigned actual_length_size;
        uint8_t *payload_at;

        if (count == 0)
            return 0;
        header_len = tag_pack(field->id, out);
        out[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
        len_start = header_len;
        min_length = get_type_min_size(field->type) * count;
        length_size_min = uint32_size(min_length);
        header_len += length_size_min;
        payload_at = out + header_len;

        switch (field->type) {
        case PROTOBUF_C_TYPE_SFIXED32:
        case PROTOBUF_C_TYPE_FIXED32:
        case PROTOBUF_C_TYPE_FLOAT:
            copy_to_little_endian_32(payload_at, array, count);
            payload_at += count * 4;
            break;
        case PROTOBUF_C_TYPE_SFIXED64:
        case PROTOBUF_C_TYPE_FIXED64:
        case PROTOBUF_C_TYPE_DOUBLE:
            copy_to_little_endian_64(payload_at, array, count);
            payload_at += count * 8;
            break;
        case PROTOBUF_C_TYPE_ENUM:
        case PROTOBUF_C_TYPE_INT32: {
            const int32_t *arr = (const int32_t *) array;
            for (i = 0; i < count; i++)
                payload_at += int32_pack(arr[i], payload_at);
            break;
        }
        case PROTOBUF_C_TYPE_SINT32: {
            const int32_t *arr = (const int32_t *) array;
            for (i = 0; i < count; i++)
                payload_at += sint32_pack(arr[i], payload_at);
            break;
        }
        case PROTOBUF_C_TYPE_SINT64: {
            const _int64_t *arr = (const _int64_t *) array;
            for (i = 0; i < count; i++)
                payload_at += sint64_pack(arr[i], payload_at);
            break;
        }
        case PROTOBUF_C_TYPE_UINT32: {
            const uint32_t *arr = (const uint32_t *) array;
            for (i = 0; i < count; i++)
                payload_at += uint32_pack(arr[i], payload_at);
            break;
        }
        case PROTOBUF_C_TYPE_INT64:
        case PROTOBUF_C_TYPE_UINT64: {
            const _uint64_t *arr = (const _uint64_t *) array;
            for (i = 0; i < count; i++)
                payload_at += uint64_pack(arr[i], payload_at);
            break;
        }
        case PROTOBUF_C_TYPE_BOOL: {
            const protobuf_c_boolean *arr = (const protobuf_c_boolean *) array;
            for (i = 0; i < count; i++)
                payload_at += boolean_pack(arr[i], payload_at);
            break;
        }
        default:
            PROTOBUF_C__ASSERT_NOT_REACHED();
        }

        payload_len = payload_at - (out + header_len);
        actual_length_size = uint32_size(payload_len);
        if (length_size_min != actual_length_size) {
            assert(actual_length_size == length_size_min + 1);
            memmove(out + header_len + 1, out + header_len,
                payload_len);
            header_len++;
        }
        uint32_pack(payload_len, out + len_start);
        return header_len + payload_len;
    } else {
        /* not "packed" cased */
        /* CONSIDER: optimize this case a bit (by putting the loop inside the switch) */
        size_t rv = 0;
        unsigned siz = sizeof_elt_in_repeated_array(field->type);

        for (i = 0; i < count; i++) {
            rv += required_field_pack(field, array, out + rv);
            array = (char *)array + siz;
        }
        return rv;
    }
}

static size_t
unknown_field_pack(const ProtobufCMessageUnknownField *field, uint8_t *out)
{
    size_t rv = tag_pack(field->tag, out);
    out[0] |= field->wire_type;
    memcpy(out + rv, field->data, field->len);
    return rv + field->len;
}

/**@}*/

size_t
protobuf_c_message_pack(const ProtobufCMessage *message, uint8_t *out)
{
    unsigned i;
    size_t rv = 0;

    ASSERT_IS_MESSAGE(message);
    for (i = 0; i < message->descriptor->n_fields; i++) {
        const ProtobufCFieldDescriptor *field =
            message->descriptor->fields + i;
        const void *member = ((const char *) message) + field->offset;

        /*
         * It doesn't hurt to compute qmember (a pointer to the
         * quantifier field of the structure), but the pointer is only
         * valid if the field is:
         *  - a repeated field, or
         *  - a field that is part of a oneof
         *  - an optional field that isn't a pointer type
         * (Meaning: not a message or a string).
         */
        const void *qmember =
            ((const char *) message) + field->quantifier_offset;

        if (field->label == PROTOBUF_C_LABEL_REQUIRED) {
            rv += required_field_pack(field, member, out + rv);
        } else if ((field->label == PROTOBUF_C_LABEL_OPTIONAL ||
                field->label == PROTOBUF_C_LABEL_NONE) &&
               (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_ONEOF))) {
            rv += oneof_field_pack(
                field,
                *(const uint32_t *) qmember,
                member,
                out + rv
            );
        } else if (field->label == PROTOBUF_C_LABEL_OPTIONAL) {
            rv += optional_field_pack(
                field,
                *(const protobuf_c_boolean *) qmember,
                member,
                out + rv
            );
        } else if (field->label == PROTOBUF_C_LABEL_NONE) {
            rv += unlabeled_field_pack(field, member, out + rv);
        } else {
            rv += repeated_field_pack(field, *(const size_t *) qmember,
                member, out + rv);
        }
    }
    for (i = 0; i < message->n_unknown_fields; i++)
        rv += unknown_field_pack(&message->unknown_fields[i], out + rv);
    return rv;
}

/**
 * \defgroup packbuf protobuf_c_message_pack_to_buffer() implementation
 *
 * Routines mainly used by protobuf_c_message_pack_to_buffer().
 *
 * \ingroup internal
 * @{
 */

/**
 * Pack a required field to a virtual buffer.
 *
 * \param field
 *      Field descriptor.
 * \param member
 *      The element to be packed.
 * \param[out] buffer
 *      Virtual buffer to append data to.
 * \return
 *      Number of bytes packed.
 */
static size_t
required_field_pack_to_buffer(const ProtobufCFieldDescriptor *field,
                  const void *member, ProtobufCBuffer *buffer)
{
    size_t rv;
    uint8_t scratch[MAX_UINT64_ENCODED_SIZE * 2];

    rv = tag_pack(field->id, scratch);
    switch (field->type) {
    case PROTOBUF_C_TYPE_SINT32:
        scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        rv += sint32_pack(*(const int32_t *) member, scratch + rv);
        buffer->append(buffer, rv, scratch);
        break;
    case PROTOBUF_C_TYPE_ENUM:
    case PROTOBUF_C_TYPE_INT32:
        scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        rv += int32_pack(*(const int32_t *) member, scratch + rv);
        buffer->append(buffer, rv, scratch);
        break;
    case PROTOBUF_C_TYPE_UINT32:
        scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        rv += uint32_pack(*(const uint32_t *) member, scratch + rv);
        buffer->append(buffer, rv, scratch);
        break;
    case PROTOBUF_C_TYPE_SINT64:
        scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        rv += sint64_pack(*(const _int64_t *) member, scratch + rv);
        buffer->append(buffer, rv, scratch);
        break;
    case PROTOBUF_C_TYPE_INT64:
    case PROTOBUF_C_TYPE_UINT64:
        scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        rv += uint64_pack(*(const _uint64_t *) member, scratch + rv);
        buffer->append(buffer, rv, scratch);
        break;
    case PROTOBUF_C_TYPE_SFIXED32:
    case PROTOBUF_C_TYPE_FIXED32:
    case PROTOBUF_C_TYPE_FLOAT:
        scratch[0] |= PROTOBUF_C_WIRE_TYPE_32BIT;
        rv += fixed32_pack(*(const uint32_t *) member, scratch + rv);
        buffer->append(buffer, rv, scratch);
        break;
    case PROTOBUF_C_TYPE_SFIXED64:
    case PROTOBUF_C_TYPE_FIXED64:
    case PROTOBUF_C_TYPE_DOUBLE:
        scratch[0] |= PROTOBUF_C_WIRE_TYPE_64BIT;
        rv += fixed64_pack(*(const _uint64_t *) member, scratch + rv);
        buffer->append(buffer, rv, scratch);
        break;
    case PROTOBUF_C_TYPE_BOOL:
        scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
        rv += boolean_pack(*(const protobuf_c_boolean *) member, scratch + rv);
        buffer->append(buffer, rv, scratch);
        break;
    case PROTOBUF_C_TYPE_STRING: {
        const char *str = *(char *const *) member;
        size_t sublen = str ? strlen(str) : 0;

        scratch[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
        rv += uint32_pack(sublen, scratch + rv);
        buffer->append(buffer, rv, scratch);
        buffer->append(buffer, sublen, (const uint8_t *) str);
        rv += sublen;
        break;
    }
    case PROTOBUF_C_TYPE_BYTES: {
        const ProtobufCBinaryData *bd = ((const ProtobufCBinaryData *) member);
        size_t sublen = bd->len;

        scratch[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
        rv += uint32_pack(sublen, scratch + rv);
        buffer->append(buffer, rv, scratch);
        buffer->append(buffer, sublen, bd->data);
        rv += sublen;
        break;
    }
    case PROTOBUF_C_TYPE_MESSAGE: {
        uint8_t simple_buffer_scratch[256];
        size_t sublen;
        const ProtobufCMessage *msg = *(ProtobufCMessage * const *) member;
        ProtobufCBufferSimple simple_buffer =
            PROTOBUF_C_BUFFER_SIMPLE_INIT(simple_buffer_scratch);

        scratch[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
        if (msg == NULL)
            sublen = 0;
        else
            sublen = protobuf_c_message_pack_to_buffer(msg, &simple_buffer.base);
        rv += uint32_pack(sublen, scratch + rv);
        buffer->append(buffer, rv, scratch);
        buffer->append(buffer, sublen, simple_buffer.data);
        rv += sublen;
        PROTOBUF_C_BUFFER_SIMPLE_CLEAR(&simple_buffer);
        break;
    }
    default:
        PROTOBUF_C__ASSERT_NOT_REACHED();
    }
    return rv;
}

/**
 * Pack a oneof field to a buffer. Only packs the field that is selected by the case enum.
 *
 * \param field
 *      Field descriptor.
 * \param oneof_case
 *      Enum value that selects the field in the oneof.
 * \param member
 *      The element to be packed.
 * \param[out] buffer
 *      Virtual buffer to append data to.
 * \return
 *      Number of bytes serialised to `buffer`.
 */
static size_t
oneof_field_pack_to_buffer(const ProtobufCFieldDescriptor *field,
               uint32_t oneof_case,
               const void *member, ProtobufCBuffer *buffer)
{
    if (oneof_case != field->id) {
        return 0;
    }
    if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
        field->type == PROTOBUF_C_TYPE_STRING)
    {
        const void *ptr = *(const void *const *) member;
        if (ptr == NULL || ptr == field->default_value)
            return 0;
    }
    return required_field_pack_to_buffer(field, member, buffer);
}

/**
 * Pack an optional field to a buffer.
 *
 * \param field
 *      Field descriptor.
 * \param has
 *      Whether the field is set.
 * \param member
 *      The element to be packed.
 * \param[out] buffer
 *      Virtual buffer to append data to.
 * \return
 *      Number of bytes serialised to `buffer`.
 */
static size_t
optional_field_pack_to_buffer(const ProtobufCFieldDescriptor *field,
                  const protobuf_c_boolean has,
                  const void *member, ProtobufCBuffer *buffer)
{
    if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
        field->type == PROTOBUF_C_TYPE_STRING)
    {
        const void *ptr = *(const void *const *) member;
        if (ptr == NULL || ptr == field->default_value)
            return 0;
    } else {
        if (!has)
            return 0;
    }
    return required_field_pack_to_buffer(field, member, buffer);
}

/**
 * Pack an unlabeled field to a buffer.
 *
 * \param field
 *      Field descriptor.
 * \param member
 *      The element to be packed.
 * \param[out] buffer
 *      Virtual buffer to append data to.
 * \return
 *      Number of bytes serialised to `buffer`.
 */
static size_t
unlabeled_field_pack_to_buffer(const ProtobufCFieldDescriptor *field,
                   const void *member, ProtobufCBuffer *buffer)
{
    if (field_is_zeroish(field, member))
        return 0;
    return required_field_pack_to_buffer(field, member, buffer);
}

/**
 * Get the packed size of an array of same field type.
 *
 * \param field
 *      Field descriptor.
 * \param count
 *      Number of elements of this type.
 * \param array
 *      The elements to get the size of.
 * \return
 *      Number of bytes required.
 */
static size_t
get_packed_payload_length(const ProtobufCFieldDescriptor *field,
              unsigned count, const void *array)
{
    unsigned rv = 0;
    unsigned i;

    switch (field->type) {
    case PROTOBUF_C_TYPE_SFIXED32:
    case PROTOBUF_C_TYPE_FIXED32:
    case PROTOBUF_C_TYPE_FLOAT:
        return count * 4;
    case PROTOBUF_C_TYPE_SFIXED64:
    case PROTOBUF_C_TYPE_FIXED64:
    case PROTOBUF_C_TYPE_DOUBLE:
        return count * 8;
    case PROTOBUF_C_TYPE_ENUM:
    case PROTOBUF_C_TYPE_INT32: {
        const int32_t *arr = (const int32_t *) array;
        for (i = 0; i < count; i++)
            rv += int32_size(arr[i]);
        break;
    }
    case PROTOBUF_C_TYPE_SINT32: {
        const int32_t *arr = (const int32_t *) array;
        for (i = 0; i < count; i++)
            rv += sint32_size(arr[i]);
        break;
    }
    case PROTOBUF_C_TYPE_UINT32: {
        const uint32_t *arr = (const uint32_t *) array;
        for (i = 0; i < count; i++)
            rv += uint32_size(arr[i]);
        break;
    }
    case PROTOBUF_C_TYPE_SINT64: {
        const _int64_t *arr = (const _int64_t *) array;
        for (i = 0; i < count; i++)
            rv += sint64_size(arr[i]);
        break;
    }
    case PROTOBUF_C_TYPE_INT64:
    case PROTOBUF_C_TYPE_UINT64: {
        const _uint64_t *arr = (const _uint64_t *) array;
        for (i = 0; i < count; i++)
            rv += uint64_size(arr[i]);
        break;
    }
    case PROTOBUF_C_TYPE_BOOL:
        return count;
    default:
        PROTOBUF_C__ASSERT_NOT_REACHED();
    }
    return rv;
}

/**
 * Pack an array of same field type to a virtual buffer.
 *
 * \param field
 *      Field descriptor.
 * \param count
 *      Number of elements of this type.
 * \param array
 *      The elements to get the size of.
 * \param[out] buffer
 *      Virtual buffer to append data to.
 * \return
 *      Number of bytes packed.
 */
static size_t
pack_buffer_packed_payload(const ProtobufCFieldDescriptor *field,
               unsigned count, const void *array,
               ProtobufCBuffer *buffer)
{
    uint8_t scratch[16];
    size_t rv = 0;
    unsigned i;

    switch (field->type) {
    case PROTOBUF_C_TYPE_SFIXED32:
    case PROTOBUF_C_TYPE_FIXED32:
    case PROTOBUF_C_TYPE_FLOAT:
#if !defined(WORDS_BIGENDIAN)
        rv = count * 4;
        goto no_packing_needed;
#else
        for (i = 0; i < count; i++) {
            unsigned len = fixed32_pack(((uint32_t *) array)[i], scratch);
            buffer->append(buffer, len, scratch);
            rv += len;
        }
        break;
#endif
    case PROTOBUF_C_TYPE_SFIXED64:
    case PROTOBUF_C_TYPE_FIXED64:
    case PROTOBUF_C_TYPE_DOUBLE:
#if !defined(WORDS_BIGENDIAN)
        rv = count * 8;
        goto no_packing_needed;
#else
        for (i = 0; i < count; i++) {
            unsigned len = fixed64_pack(((_uint64_t *) array)[i], scratch);
            buffer->append(buffer, len, scratch);
            rv += len;
        }
        break;
#endif
    case PROTOBUF_C_TYPE_ENUM:
    case PROTOBUF_C_TYPE_INT32:
        for (i = 0; i < count; i++) {
            unsigned len = int32_pack(((int32_t *) array)[i], scratch);
            buffer->append(buffer, len, scratch);
            rv += len;
        }
        break;
    case PROTOBUF_C_TYPE_SINT32:
        for (i = 0; i < count; i++) {
            unsigned len = sint32_pack(((int32_t *) array)[i], scratch);
            buffer->append(buffer, len, scratch);
            rv += len;
        }
        break;
    case PROTOBUF_C_TYPE_UINT32:
        for (i = 0; i < count; i++) {
            unsigned len = uint32_pack(((uint32_t *) array)[i], scratch);
            buffer->append(buffer, len, scratch);
            rv += len;
        }
        break;
    case PROTOBUF_C_TYPE_SINT64:
        for (i = 0; i < count; i++) {
            unsigned len = sint64_pack(((_int64_t *) array)[i], scratch);
            buffer->append(buffer, len, scratch);
            rv += len;
        }
        break;
    case PROTOBUF_C_TYPE_INT64:
    case PROTOBUF_C_TYPE_UINT64:
        for (i = 0; i < count; i++) {
            unsigned len = uint64_pack(((_uint64_t *) array)[i], scratch);
            buffer->append(buffer, len, scratch);
            rv += len;
        }
        break;
    case PROTOBUF_C_TYPE_BOOL:
        for (i = 0; i < count; i++) {
            unsigned len = boolean_pack(((protobuf_c_boolean *) array)[i], scratch);
            buffer->append(buffer, len, scratch);
            rv += len;
        }
        return count;
    default:
        PROTOBUF_C__ASSERT_NOT_REACHED();
    }
    return rv;

#if !defined(WORDS_BIGENDIAN)
no_packing_needed:
    buffer->append(buffer, rv, array);
    return rv;
#endif
}

static size_t
repeated_field_pack_to_buffer(const ProtobufCFieldDescriptor *field,
                  unsigned count, const void *member,
                  ProtobufCBuffer *buffer)
{
    char *array = *(char * const *) member;

    if (count == 0)
        return 0;
    if (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED)) {
        uint8_t scratch[MAX_UINT64_ENCODED_SIZE * 2];
        size_t rv = tag_pack(field->id, scratch);
        size_t payload_len = get_packed_payload_length(field, count, array);
        size_t tmp;

        scratch[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
        rv += uint32_pack(payload_len, scratch + rv);
        buffer->append(buffer, rv, scratch);
        tmp = pack_buffer_packed_payload(field, count, array, buffer);
        if(tmp != payload_len)
            Panic();
        return rv + payload_len;
    } else {
        size_t siz;
        unsigned i;
        /* CONSIDER: optimize this case a bit (by putting the loop inside the switch) */
        unsigned rv = 0;

        siz = sizeof_elt_in_repeated_array(field->type);
        for (i = 0; i < count; i++) {
            rv += required_field_pack_to_buffer(field, array, buffer);
            array += siz;
        }
        return rv;
    }
}

static size_t
unknown_field_pack_to_buffer(const ProtobufCMessageUnknownField *field,
                 ProtobufCBuffer *buffer)
{
    uint8_t header[MAX_UINT64_ENCODED_SIZE];
    size_t rv = tag_pack(field->tag, header);

    header[0] |= field->wire_type;
    buffer->append(buffer, rv, header);
    buffer->append(buffer, field->len, field->data);
    return rv + field->len;
}

/**@}*/

size_t
protobuf_c_message_pack_to_buffer(const ProtobufCMessage *message,
                  ProtobufCBuffer *buffer)
{
    unsigned i;
    size_t rv = 0;

    ASSERT_IS_MESSAGE(message);
    for (i = 0; i < message->descriptor->n_fields; i++) {
        const ProtobufCFieldDescriptor *field =
            message->descriptor->fields + i;
        const void *member =
            ((const char *) message) + field->offset;
        const void *qmember =
            ((const char *) message) + field->quantifier_offset;

        if (field->label == PROTOBUF_C_LABEL_REQUIRED) {
            rv += required_field_pack_to_buffer(field, member, buffer);
        } else if ((field->label == PROTOBUF_C_LABEL_OPTIONAL ||
                field->label == PROTOBUF_C_LABEL_NONE) &&
               (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_ONEOF))) {
            rv += oneof_field_pack_to_buffer(
                field,
                *(const uint32_t *) qmember,
                member,
                buffer
            );
        } else if (field->label == PROTOBUF_C_LABEL_OPTIONAL) {
            rv += optional_field_pack_to_buffer(
                field,
                *(const protobuf_c_boolean *) qmember,
                member,
                buffer
            );
        } else if (field->label == PROTOBUF_C_LABEL_NONE) {
            rv += unlabeled_field_pack_to_buffer(
                field,
                member,
                buffer
            );
        } else {
            rv += repeated_field_pack_to_buffer(
                field,
                *(const size_t *) qmember,
                member,
                buffer
            );
        }
    }
    for (i = 0; i < message->n_unknown_fields; i++)
        rv += unknown_field_pack_to_buffer(&message->unknown_fields[i], buffer);

    return rv;
}

/**
 * \defgroup unpack unpacking implementation
 *
 * Routines mainly used by the unpacking functions.
 *
 * \ingroup internal
 * @{
 */

static inline int
int_range_lookup(unsigned n_ranges, const ProtobufCIntRange *ranges, int value)
{
    unsigned n;
    unsigned start;

    if (n_ranges == 0)
        return -1;
    start = 0;
    n = n_ranges;
    while (n > 1) {
        unsigned mid = start + n / 2;

        if (value < ranges[mid].start_value) {
            n = mid - start;
        } else if (value >= ranges[mid].start_value +
               (int) (ranges[mid + 1].orig_index -
                  ranges[mid].orig_index))
        {
            unsigned new_start = mid + 1;
            n = start + n - new_start;
            start = new_start;
        } else
            return (value - ranges[mid].start_value) +
                ranges[mid].orig_index;
    }
    if (n > 0) {
        unsigned start_orig_index = ranges[start].orig_index;
        unsigned range_size =
            ranges[start + 1].orig_index - start_orig_index;

        if (ranges[start].start_value <= value &&
            value < (int) (ranges[start].start_value + range_size))
        {
            return (value - ranges[start].start_value) +
                start_orig_index;
        }
    }
    return -1;
}

static size_t
parse_tag_and_wiretype(size_t len,
               const uint8_t *data,
               uint32_t *tag_out,
               ProtobufCWireType *wiretype_out)
{
    unsigned max_rv = len > 5 ? 5 : len;
    uint32_t tag = (data[0] & 0x7f) >> 3;
    unsigned shift = 4;
    unsigned rv;

    *wiretype_out = data[0] & 7;
    if ((data[0] & 0x80) == 0) {
        *tag_out = tag;
        return 1;
    }
    for (rv = 1; rv < max_rv; rv++) {
        if (data[rv] & 0x80) {
            tag |= (data[rv] & 0x7f) << shift;
            shift += 7;
        } else {
            tag |= data[rv] << shift;
            *tag_out = tag;
            return rv + 1;
        }
    }
    return 0; /* error: bad header */
}

/* sizeof(ScannedMember) must be <= (1UL<<BOUND_SIZEOF_SCANNED_MEMBER_LOG2) */
#define BOUND_SIZEOF_SCANNED_MEMBER_LOG2 5
typedef struct _ScannedMember ScannedMember;
/** Field as it's being read. */
struct _ScannedMember {
    uint32_t tag;              /**< Field tag. */
    uint8_t wire_type;         /**< Field type. */
    uint8_t length_prefix_len; /**< Prefix length. */
    const ProtobufCFieldDescriptor *field; /**< Field descriptor. */
    size_t len;                /**< Field length. */
    const uint8_t *data;       /**< Pointer to field data. */
};

static inline uint32_t
scan_length_prefixed_data(size_t len, const uint8_t *data,
              size_t *prefix_len_out)
{
    unsigned hdr_max = len < 5 ? len : 5;
    unsigned hdr_len;
    uint32_t val = 0;
    unsigned i;
    unsigned shift = 0;

    for (i = 0; i < hdr_max; i++) {
        val |= (data[i] & 0x7f) << shift;
        shift += 7;
        if ((data[i] & 0x80) == 0)
            break;
    }
    if (i == hdr_max) {
        PROTOBUF_C_UNPACK_ERROR("error parsing length for length-prefixed data");
        return 0;
    }
    hdr_len = i + 1;
    *prefix_len_out = hdr_len;
    if (hdr_len + val > len) {
        PROTOBUF_C_UNPACK_ERROR("data too short after length-prefix of %u", val);
        return 0;
    }
    return hdr_len + val;
}

static size_t
max_b128_numbers(size_t len, const uint8_t *data)
{
    size_t rv = 0;
    while (len--)
        if ((*data++ & 0x80) == 0)
            ++rv;
    return rv;
}

/**@}*/

/**
 * Merge earlier message into a latter message.
 *
 * For numeric types and strings, if the same value appears multiple
 * times, the parser accepts the last value it sees. For embedded
 * message fields, the parser merges multiple instances of the same
 * field. That is, all singular scalar fields in the latter instance
 * replace those in the former, singular embedded messages are merged,
 * and repeated fields are concatenated.
 *
 * The earlier message should be freed after calling this function, as
 * some of its fields may have been reused and changed to their default
 * values during the merge.
 */
static protobuf_c_boolean
merge_messages(ProtobufCMessage *earlier_msg,
           ProtobufCMessage *latter_msg,
           ProtobufCAllocator *allocator)
{
    unsigned i;
    const ProtobufCFieldDescriptor *fields =
        latter_msg->descriptor->fields;
    for (i = 0; i < latter_msg->descriptor->n_fields; i++) {
        if (fields[i].label == PROTOBUF_C_LABEL_REPEATED) {
            size_t *n_earlier =
                STRUCT_MEMBER_PTR(size_t, earlier_msg,
                          fields[i].quantifier_offset);
            uint8_t **p_earlier =
                STRUCT_MEMBER_PTR(uint8_t *, earlier_msg,
                          fields[i].offset);
            size_t *n_latter =
                STRUCT_MEMBER_PTR(size_t, latter_msg,
                          fields[i].quantifier_offset);
            uint8_t **p_latter =
                STRUCT_MEMBER_PTR(uint8_t *, latter_msg,
                          fields[i].offset);

            if (*n_earlier > 0) {
                if (*n_latter > 0) {
                    /* Concatenate the repeated field */
                    size_t el_size =
                        sizeof_elt_in_repeated_array(fields[i].type);
                    uint8_t *new_field;

                    new_field = do_alloc(allocator,
                        (*n_earlier + *n_latter) * el_size);
                    if (!new_field)
                        return FALSE;

                    memcpy(new_field, *p_earlier,
                           *n_earlier * el_size);
                    memcpy(new_field +
                           *n_earlier * el_size,
                           *p_latter,
                           *n_latter * el_size);

                    do_free(allocator, *p_latter);
                    do_free(allocator, *p_earlier);
                    *p_latter = new_field;
                    *n_latter = *n_earlier + *n_latter;
                } else {
                    /* Zero copy the repeated field from the earlier message */
                    *n_latter = *n_earlier;
                    *p_latter = *p_earlier;
                }
                /* Make sure the field does not get double freed */
                *n_earlier = 0;
                *p_earlier = 0;
            }
        } else if (fields[i].label == PROTOBUF_C_LABEL_OPTIONAL ||
               fields[i].label == PROTOBUF_C_LABEL_NONE) {
            const ProtobufCFieldDescriptor *field;
            uint32_t *earlier_case_p = STRUCT_MEMBER_PTR(uint32_t,
                                     earlier_msg,
                                     fields[i].
                                     quantifier_offset);
            uint32_t *latter_case_p = STRUCT_MEMBER_PTR(uint32_t,
                                    latter_msg,
                                    fields[i].
                                    quantifier_offset);
            protobuf_c_boolean need_to_merge = FALSE;
            void *earlier_elem;
            void *latter_elem;
            const void *def_val;

            if (fields[i].flags & PROTOBUF_C_FIELD_FLAG_ONEOF) {
                if (*latter_case_p == 0) {
                    /* lookup correct oneof field */
                    int field_index =
                        int_range_lookup(
                            latter_msg->descriptor
                            ->n_field_ranges,
                            latter_msg->descriptor
                            ->field_ranges,
                            *earlier_case_p);
                    if (field_index < 0)
                        return FALSE;
                    field = latter_msg->descriptor->fields +
                        field_index;
                } else {
                    /* Oneof is present in the latter message, move on */
                    continue;
                }
            } else {
                field = &fields[i];
            }

            earlier_elem = STRUCT_MEMBER_P(earlier_msg, field->offset);
            latter_elem = STRUCT_MEMBER_P(latter_msg, field->offset);
            def_val = field->default_value;

            switch (field->type) {
            case PROTOBUF_C_TYPE_MESSAGE: {
                ProtobufCMessage *em = *(ProtobufCMessage **) earlier_elem;
                ProtobufCMessage *lm = *(ProtobufCMessage **) latter_elem;
                if (em != NULL) {
                    if (lm != NULL) {
                        if (!merge_messages(em, lm, allocator))
                            return FALSE;
                        /* Already merged */
                        need_to_merge = FALSE;
                    } else {
                        /* Zero copy the message */
                        need_to_merge = TRUE;
                    }
                }
                break;
            }
            case PROTOBUF_C_TYPE_BYTES: {
                uint8_t *e_data =
                    ((ProtobufCBinaryData *) earlier_elem)->data;
                uint8_t *l_data =
                    ((ProtobufCBinaryData *) latter_elem)->data;
                const ProtobufCBinaryData *d_bd =
                    (ProtobufCBinaryData *) def_val;

                need_to_merge =
                    (e_data != NULL &&
                     (d_bd == NULL ||
                      e_data != d_bd->data)) &&
                    (l_data == NULL ||
                     (d_bd != NULL &&
                      l_data == d_bd->data));
                break;
            }
            case PROTOBUF_C_TYPE_STRING: {
                char *e_str = *(char **) earlier_elem;
                char *l_str = *(char **) latter_elem;
                const char *d_str = def_val;

                need_to_merge = e_str != d_str && l_str == d_str;
                break;
            }
            default: {
                /* Could be has field or case enum, the logic is
                 * equivalent, since 0 (FALSE) means not set for
                 * oneof */
                need_to_merge = (*earlier_case_p != 0) &&
                        (*latter_case_p == 0);
                break;
            }
            }

            if (need_to_merge) {
                size_t el_size =
                    sizeof_elt_in_repeated_array(field->type);
                memcpy(latter_elem, earlier_elem, el_size);
                /*
                 * Reset the element from the old message to 0
                 * to make sure earlier message deallocation
                 * doesn't corrupt zero-copied data in the new
                 * message, earlier message will be freed after
                 * this function is called anyway
                 */
                memset(earlier_elem, 0, el_size);

                if (field->quantifier_offset != 0) {
                    /* Set the has field or the case enum,
                     * if applicable */
                    *latter_case_p = *earlier_case_p;
                    *earlier_case_p = 0;
                }
            }
        }
    }
    return TRUE;
}

/**
 * Count packed elements.
 *
 * Given a raw slab of packed-repeated values, determine the number of
 * elements. This function detects certain kinds of errors but not
 * others; the remaining error checking is done by
 * parse_packed_repeated_member().
 */
static protobuf_c_boolean
count_packed_elements(ProtobufCType type,
              size_t len, const uint8_t *data, size_t *count_out)
{
    switch (type) {
    case PROTOBUF_C_TYPE_SFIXED32:
    case PROTOBUF_C_TYPE_FIXED32:
    case PROTOBUF_C_TYPE_FLOAT:
        if (len % 4 != 0) {
            PROTOBUF_C_UNPACK_ERROR("length must be a multiple of 4 for fixed-length 32-bit types");
            return FALSE;
        }
        *count_out = len / 4;
        return TRUE;
    case PROTOBUF_C_TYPE_SFIXED64:
    case PROTOBUF_C_TYPE_FIXED64:
    case PROTOBUF_C_TYPE_DOUBLE:
        if (len % 8 != 0) {
            PROTOBUF_C_UNPACK_ERROR("length must be a multiple of 8 for fixed-length 64-bit types");
            return FALSE;
        }
        *count_out = len / 8;
        return TRUE;
    case PROTOBUF_C_TYPE_ENUM:
    case PROTOBUF_C_TYPE_INT32:
    case PROTOBUF_C_TYPE_SINT32:
    case PROTOBUF_C_TYPE_UINT32:
    case PROTOBUF_C_TYPE_INT64:
    case PROTOBUF_C_TYPE_SINT64:
    case PROTOBUF_C_TYPE_UINT64:
        *count_out = max_b128_numbers(len, data);
        return TRUE;
    case PROTOBUF_C_TYPE_BOOL:
        *count_out = len;
        return TRUE;
    case PROTOBUF_C_TYPE_STRING:
    case PROTOBUF_C_TYPE_BYTES:
    case PROTOBUF_C_TYPE_MESSAGE:
    default:
        PROTOBUF_C_UNPACK_ERROR("bad protobuf-c type %u for packed-repeated", type);
        return FALSE;
    }
}

static inline uint32_t
parse_uint32(unsigned len, const uint8_t *data)
{
    uint32_t rv = data[0] & 0x7f;
    if (len > 1) {
        rv |= ((uint32_t) (data[1] & 0x7f) << 7);
        if (len > 2) {
            rv |= ((uint32_t) (data[2] & 0x7f) << 14);
            if (len > 3) {
                rv |= ((uint32_t) (data[3] & 0x7f) << 21);
                if (len > 4)
                    rv |= ((uint32_t) (data[4]) << 28);
            }
        }
    }
    return rv;
}

static inline uint32_t
parse_int32(unsigned len, const uint8_t *data)
{
    return parse_uint32(len, data);
}

static inline int32_t
unzigzag32(uint32_t v)
{
    if (v & 1)
        return -(v >> 1) - 1;
    else
        return v >> 1;
}

static inline uint32_t
parse_fixed_uint32(const uint8_t *data)
{
#if !defined(WORDS_BIGENDIAN)
    uint32_t t;
    memcpy(&t, data, 4);
    return t;
#else
    return data[0] |
        ((uint32_t) (data[1]) << 8) |
        ((uint32_t) (data[2]) << 16) |
        ((uint32_t) (data[3]) << 24);
#endif
}

static _uint64_t
parse_uint64(unsigned len, const uint8_t *data)
{
    unsigned shift, i;
    _uint64_t rv;

    if (len < 5)
        return parse_uint32(len, data);
    rv = ((_uint64_t) (data[0] & 0x7f)) |
        ((_uint64_t) (data[1] & 0x7f) << 7) |
        ((_uint64_t) (data[2] & 0x7f) << 14) |
        ((_uint64_t) (data[3] & 0x7f) << 21);
    shift = 28;
    for (i = 4; i < len; i++) {
        rv |= (((_uint64_t) (data[i] & 0x7f)) << shift);
        shift += 7;
    }
    return rv;
}

static inline _int64_t
unzigzag64(_uint64_t v)
{
    if (v & 1)
        return -(v >> 1) - 1;
    else
        return v >> 1;
}

static inline _uint64_t
parse_fixed_uint64(const uint8_t *data)
{
#if !defined(WORDS_BIGENDIAN)
    _uint64_t t;
    memcpy(&t, data, 8);
    return t;
#else
    return (_uint64_t) parse_fixed_uint32(data) |
        (((_uint64_t) parse_fixed_uint32(data + 4)) << 32);
#endif
}

static protobuf_c_boolean
parse_boolean(unsigned len, const uint8_t *data)
{
    unsigned i;
    for (i = 0; i < len; i++)
        if (data[i] & 0x7f)
            return TRUE;
    return FALSE;
}

static protobuf_c_boolean
parse_required_member(ScannedMember *scanned_member,
              void *member,
              ProtobufCAllocator *allocator,
              protobuf_c_boolean maybe_clear)
{
    unsigned len = scanned_member->len;
    const uint8_t *data = scanned_member->data;
    ProtobufCWireType wire_type = scanned_member->wire_type;

    switch (scanned_member->field->type) {
    case PROTOBUF_C_TYPE_ENUM:
    case PROTOBUF_C_TYPE_INT32:
        if (wire_type != PROTOBUF_C_WIRE_TYPE_VARINT)
            return FALSE;
        *(int32_t *) member = parse_int32(len, data);
        return TRUE;
    case PROTOBUF_C_TYPE_UINT32:
        if (wire_type != PROTOBUF_C_WIRE_TYPE_VARINT)
            return FALSE;
        *(uint32_t *) member = parse_uint32(len, data);
        return TRUE;
    case PROTOBUF_C_TYPE_SINT32:
        if (wire_type != PROTOBUF_C_WIRE_TYPE_VARINT)
            return FALSE;
        *(int32_t *) member = unzigzag32(parse_uint32(len, data));
        return TRUE;
    case PROTOBUF_C_TYPE_SFIXED32:
    case PROTOBUF_C_TYPE_FIXED32:
    case PROTOBUF_C_TYPE_FLOAT:
        if (wire_type != PROTOBUF_C_WIRE_TYPE_32BIT)
            return FALSE;
        *(uint32_t *) member = parse_fixed_uint32(data);
        return TRUE;
    case PROTOBUF_C_TYPE_INT64:
    case PROTOBUF_C_TYPE_UINT64:
        if (wire_type != PROTOBUF_C_WIRE_TYPE_VARINT)
            return FALSE;
        *(_uint64_t *) member = parse_uint64(len, data);
        return TRUE;
    case PROTOBUF_C_TYPE_SINT64:
        if (wire_type != PROTOBUF_C_WIRE_TYPE_VARINT)
            return FALSE;
        *(_int64_t *) member = unzigzag64(parse_uint64(len, data));
        return TRUE;
    case PROTOBUF_C_TYPE_SFIXED64:
    case PROTOBUF_C_TYPE_FIXED64:
    case PROTOBUF_C_TYPE_DOUBLE:
        if (wire_type != PROTOBUF_C_WIRE_TYPE_64BIT)
            return FALSE;
        *(_uint64_t *) member = parse_fixed_uint64(data);
        return TRUE;
    case PROTOBUF_C_TYPE_BOOL:
        *(protobuf_c_boolean *) member = parse_boolean(len, data);
        return TRUE;
    case PROTOBUF_C_TYPE_STRING: {
        char **pstr = member;
        unsigned pref_len = scanned_member->length_prefix_len;

        if (wire_type != PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED)
            return FALSE;

        if (maybe_clear && *pstr != NULL) {
            const char *def = scanned_member->field->default_value;
            if (*pstr != NULL && *pstr != def)
                do_free(allocator, *pstr);
        }
        *pstr = do_alloc(allocator, len - pref_len + 1);
        if (*pstr == NULL)
            return FALSE;
        memcpy(*pstr, data + pref_len, len - pref_len);
        (*pstr)[len - pref_len] = 0;
        return TRUE;
    }
    case PROTOBUF_C_TYPE_BYTES: {
        ProtobufCBinaryData *bd = member;
        const ProtobufCBinaryData *def_bd;
        unsigned pref_len = scanned_member->length_prefix_len;

        if (wire_type != PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED)
            return FALSE;

        def_bd = scanned_member->field->default_value;
        if (maybe_clear &&
            bd->data != NULL &&
            (def_bd == NULL || bd->data != def_bd->data))
        {
            do_free(allocator, bd->data);
        }
        if (len - pref_len > 0) {
            bd->data = do_alloc(allocator, len - pref_len);
            if (bd->data == NULL)
                return FALSE;
            memcpy(bd->data, data + pref_len, len - pref_len);
        } else {
            bd->data = NULL;
        }
        bd->len = len - pref_len;
        return TRUE;
    }
    case PROTOBUF_C_TYPE_MESSAGE: {
        ProtobufCMessage **pmessage = member;
        ProtobufCMessage *subm;
        const ProtobufCMessage *def_mess;
        protobuf_c_boolean merge_successful = TRUE;
        unsigned pref_len = scanned_member->length_prefix_len;

        if (wire_type != PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED)
            return FALSE;

        def_mess = scanned_member->field->default_value;
        subm = protobuf_c_message_unpack(scanned_member->field->descriptor,
                         allocator,
                         len - pref_len,
                         data + pref_len);

        if (maybe_clear &&
            *pmessage != NULL &&
            *pmessage != def_mess)
        {
            if (subm != NULL)
                merge_successful = merge_messages(*pmessage, subm, allocator);
            /* Delete the previous message */
            protobuf_c_message_free_unpacked(*pmessage, allocator);
        }
        *pmessage = subm;
        if (subm == NULL || !merge_successful)
            return FALSE;
        return TRUE;
    }
    }
    return FALSE;
}

static protobuf_c_boolean
parse_oneof_member (ScannedMember *scanned_member,
            void *member,
            ProtobufCMessage *message,
            ProtobufCAllocator *allocator)
{
    uint32_t *oneof_case = STRUCT_MEMBER_PTR(uint32_t, message,
                           scanned_member->field->quantifier_offset);

    /* If we have already parsed a member of this oneof, free it. */
    if (*oneof_case != 0) {
        /* lookup field */
        int field_index =
            int_range_lookup(message->descriptor->n_field_ranges,
                     message->descriptor->field_ranges,
                     *oneof_case);
        if (field_index < 0)
            return FALSE;
        const ProtobufCFieldDescriptor *old_field =
            message->descriptor->fields + field_index;
        size_t el_size = sizeof_elt_in_repeated_array(old_field->type);

        switch (old_field->type) {
            case PROTOBUF_C_TYPE_STRING: {
            char **pstr = member;
            const char *def = old_field->default_value;
            if (*pstr != NULL && *pstr != def)
                do_free(allocator, *pstr);
            break;
            }
        case PROTOBUF_C_TYPE_BYTES: {
            ProtobufCBinaryData *bd = member;
            const ProtobufCBinaryData *def_bd = old_field->default_value;
            if (bd->data != NULL &&
               (def_bd == NULL || bd->data != def_bd->data))
            {
                do_free(allocator, bd->data);
            }
            break;
            }
        case PROTOBUF_C_TYPE_MESSAGE: {
            ProtobufCMessage **pmessage = member;
            const ProtobufCMessage *def_mess = old_field->default_value;
            if (*pmessage != NULL && *pmessage != def_mess)
                protobuf_c_message_free_unpacked(*pmessage, allocator);
            break;
            }
        default:
            break;
        }

        memset (member, 0, el_size);
    }
    if (!parse_required_member (scanned_member, member, allocator, TRUE))
        return FALSE;

    *oneof_case = scanned_member->tag;
    return TRUE;
}


static protobuf_c_boolean
parse_optional_member(ScannedMember *scanned_member,
              void *member,
              ProtobufCMessage *message,
              ProtobufCAllocator *allocator)
{
    if (!parse_required_member(scanned_member, member, allocator, TRUE))
        return FALSE;
    if (scanned_member->field->quantifier_offset != 0)
        STRUCT_MEMBER(protobuf_c_boolean,
                  message,
                  scanned_member->field->quantifier_offset) = TRUE;
    return TRUE;
}

static protobuf_c_boolean
parse_repeated_member(ScannedMember *scanned_member,
              void *member,
              ProtobufCMessage *message,
              ProtobufCAllocator *allocator)
{
    const ProtobufCFieldDescriptor *field = scanned_member->field;
    size_t *p_n = STRUCT_MEMBER_PTR(size_t, message, field->quantifier_offset);
    size_t siz = sizeof_elt_in_repeated_array(field->type);
    char *array = *(char **) member;

    if (!parse_required_member(scanned_member, array + siz * (*p_n),
                   allocator, FALSE))
    {
        return FALSE;
    }
    *p_n += 1;
    return TRUE;
}

static unsigned
scan_varint(unsigned len, const uint8_t *data)
{
    unsigned i;
    if (len > 10)
        len = 10;
    for (i = 0; i < len; i++)
        if ((data[i] & 0x80) == 0)
            break;
    if (i == len)
        return 0;
    return i + 1;
}

static protobuf_c_boolean
parse_packed_repeated_member(ScannedMember *scanned_member,
                 void *member,
                 ProtobufCMessage *message)
{
    const ProtobufCFieldDescriptor *field = scanned_member->field;
    size_t *p_n = STRUCT_MEMBER_PTR(size_t, message, field->quantifier_offset);
    size_t siz = sizeof_elt_in_repeated_array(field->type);
    void *array = *(char **) member + siz * (*p_n);
    const uint8_t *at = scanned_member->data + scanned_member->length_prefix_len;
    size_t rem = scanned_member->len - scanned_member->length_prefix_len;
    size_t count = 0;
    unsigned i;

    switch (field->type) {
    case PROTOBUF_C_TYPE_SFIXED32:
    case PROTOBUF_C_TYPE_FIXED32:
    case PROTOBUF_C_TYPE_FLOAT:
        count = (scanned_member->len - scanned_member->length_prefix_len) / 4;
#if !defined(WORDS_BIGENDIAN)
        goto no_unpacking_needed;
#else
        for (i = 0; i < count; i++) {
            ((uint32_t *) array)[i] = parse_fixed_uint32(at);
            at += 4;
        }
        break;
#endif
    case PROTOBUF_C_TYPE_SFIXED64:
    case PROTOBUF_C_TYPE_FIXED64:
    case PROTOBUF_C_TYPE_DOUBLE:
        count = (scanned_member->len - scanned_member->length_prefix_len) / 8;
#if !defined(WORDS_BIGENDIAN)
        goto no_unpacking_needed;
#else
        for (i = 0; i < count; i++) {
            ((_uint64_t *) array)[i] = parse_fixed_uint64(at);
            at += 8;
        }
        break;
#endif
    case PROTOBUF_C_TYPE_ENUM:
    case PROTOBUF_C_TYPE_INT32:
        while (rem > 0) {
            unsigned s = scan_varint(rem, at);
            if (s == 0) {
                PROTOBUF_C_UNPACK_ERROR("bad packed-repeated int32 value");
                return FALSE;
            }
            ((int32_t *) array)[count++] = parse_int32(s, at);
            at += s;
            rem -= s;
        }
        break;
    case PROTOBUF_C_TYPE_SINT32:
        while (rem > 0) {
            unsigned s = scan_varint(rem, at);
            if (s == 0) {
                PROTOBUF_C_UNPACK_ERROR("bad packed-repeated sint32 value");
                return FALSE;
            }
            ((int32_t *) array)[count++] = unzigzag32(parse_uint32(s, at));
            at += s;
            rem -= s;
        }
        break;
    case PROTOBUF_C_TYPE_UINT32:
        while (rem > 0) {
            unsigned s = scan_varint(rem, at);
            if (s == 0) {
                PROTOBUF_C_UNPACK_ERROR("bad packed-repeated enum or uint32 value");
                return FALSE;
            }
            ((uint32_t *) array)[count++] = parse_uint32(s, at);
            at += s;
            rem -= s;
        }
        break;

    case PROTOBUF_C_TYPE_SINT64:
        while (rem > 0) {
            unsigned s = scan_varint(rem, at);
            if (s == 0) {
                PROTOBUF_C_UNPACK_ERROR("bad packed-repeated sint64 value");
                return FALSE;
            }
            ((_int64_t *) array)[count++] = unzigzag64(parse_uint64(s, at));
            at += s;
            rem -= s;
        }
        break;
    case PROTOBUF_C_TYPE_INT64:
    case PROTOBUF_C_TYPE_UINT64:
        while (rem > 0) {
            unsigned s = scan_varint(rem, at);
            if (s == 0) {
                PROTOBUF_C_UNPACK_ERROR("bad packed-repeated int64/uint64 value");
                return FALSE;
            }
            ((_int64_t *) array)[count++] = parse_uint64(s, at);
            at += s;
            rem -= s;
        }
        break;
    case PROTOBUF_C_TYPE_BOOL:
        count = rem;
        for (i = 0; i < count; i++) {
            if (at[i] > 1) {
                PROTOBUF_C_UNPACK_ERROR("bad packed-repeated boolean value");
                return FALSE;
            }
            ((protobuf_c_boolean *) array)[i] = at[i];
        }
        break;
    default:
        PROTOBUF_C__ASSERT_NOT_REACHED();
    }
    *p_n += count;
    return TRUE;

#if !defined(WORDS_BIGENDIAN)
no_unpacking_needed:
    memcpy(array, at, count * siz);
    *p_n += count;
    return TRUE;
#endif
}

static protobuf_c_boolean
is_packable_type(ProtobufCType type)
{
    return
        type != PROTOBUF_C_TYPE_STRING &&
        type != PROTOBUF_C_TYPE_BYTES &&
        type != PROTOBUF_C_TYPE_MESSAGE;
}

static protobuf_c_boolean
parse_member(ScannedMember *scanned_member,
         ProtobufCMessage *message,
         ProtobufCAllocator *allocator)
{
    const ProtobufCFieldDescriptor *field = scanned_member->field;
    void *member;

    if (field == NULL) {
        ProtobufCMessageUnknownField *ufield =
            message->unknown_fields +
            (message->n_unknown_fields++);
        ufield->tag = scanned_member->tag;
        ufield->wire_type = scanned_member->wire_type;
        ufield->len = scanned_member->len;
        ufield->data = do_alloc(allocator, scanned_member->len);
        if (ufield->data == NULL)
            return FALSE;
        memcpy(ufield->data, scanned_member->data, ufield->len);
        return TRUE;
    }
    member = (char *) message + field->offset;
    switch (field->label) {
    case PROTOBUF_C_LABEL_REQUIRED:
        return parse_required_member(scanned_member, member,
                         allocator, TRUE);
    case PROTOBUF_C_LABEL_OPTIONAL:
    case PROTOBUF_C_LABEL_NONE:
        if (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_ONEOF)) {
            return parse_oneof_member(scanned_member, member,
                          message, allocator);
        } else {
            return parse_optional_member(scanned_member, member,
                             message, allocator);
        }
    case PROTOBUF_C_LABEL_REPEATED:
        if (scanned_member->wire_type ==
            PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED &&
            (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED) ||
             is_packable_type(field->type)))
        {
            return parse_packed_repeated_member(scanned_member,
                                member, message);
        } else {
            return parse_repeated_member(scanned_member,
                             member, message,
                             allocator);
        }
    }
    PROTOBUF_C__ASSERT_NOT_REACHED();
    return 0;
}

/**
 * Initialise messages generated by old code.
 *
 * This function is used if desc->message_init == NULL (which occurs
 * for old code, and which would be useful to support allocating
 * descriptors dynamically).
 */
static void
message_init_generic(const ProtobufCMessageDescriptor *desc,
             ProtobufCMessage *message)
{
    unsigned i;

    memset(message, 0, desc->sizeof_message);
    message->descriptor = desc;
    for (i = 0; i < desc->n_fields; i++) {
        if (desc->fields[i].default_value != NULL &&
            desc->fields[i].label != PROTOBUF_C_LABEL_REPEATED)
        {
            void *field =
                STRUCT_MEMBER_P(message, desc->fields[i].offset);
            const void *dv = desc->fields[i].default_value;

            switch (desc->fields[i].type) {
            case PROTOBUF_C_TYPE_INT32:
            case PROTOBUF_C_TYPE_SINT32:
            case PROTOBUF_C_TYPE_SFIXED32:
            case PROTOBUF_C_TYPE_UINT32:
            case PROTOBUF_C_TYPE_FIXED32:
            case PROTOBUF_C_TYPE_FLOAT:
            case PROTOBUF_C_TYPE_ENUM:
                memcpy(field, dv, 4);
                break;
            case PROTOBUF_C_TYPE_INT64:
            case PROTOBUF_C_TYPE_SINT64:
            case PROTOBUF_C_TYPE_SFIXED64:
            case PROTOBUF_C_TYPE_UINT64:
            case PROTOBUF_C_TYPE_FIXED64:
            case PROTOBUF_C_TYPE_DOUBLE:
                memcpy(field, dv, 8);
                break;
            case PROTOBUF_C_TYPE_BOOL:
                memcpy(field, dv, sizeof(protobuf_c_boolean));
                break;
            case PROTOBUF_C_TYPE_BYTES:
                memcpy(field, dv, sizeof(ProtobufCBinaryData));
                break;

            case PROTOBUF_C_TYPE_STRING:
            case PROTOBUF_C_TYPE_MESSAGE:
                /*
                 * The next line essentially implements a cast
                 * from const, which is totally unavoidable.
                 */
                *(const void **) field = dv;
                break;
            }
        }
    }
}

/**@}*/

/*
 * ScannedMember slabs (an unpacking implementation detail). Before doing real
 * unpacking, we first scan through the elements to see how many there are (for
 * repeated fields), and which field to use (for non-repeated fields given
 * twice).
 *
 * In order to avoid allocations for small messages, we keep a stack-allocated
 * slab of ScannedMembers of size FIRST_SCANNED_MEMBER_SLAB_SIZE (16). After we
 * fill that up, we allocate each slab twice as large as the previous one.
 */
#define FIRST_SCANNED_MEMBER_SLAB_SIZE_LOG2 4

/*
 * The number of slabs, including the stack-allocated ones; choose the number so
 * that we would overflow if we needed a slab larger than provided.
 */
#define MAX_SCANNED_MEMBER_SLAB			\
  (sizeof(unsigned int)*8 - 1			\
   - BOUND_SIZEOF_SCANNED_MEMBER_LOG2		\
   - FIRST_SCANNED_MEMBER_SLAB_SIZE_LOG2)

#define REQUIRED_FIELD_BITMAP_SET(index)	\
    (required_fields_bitmap[(index)/8] |= (1UL<<((index)%8)))

#define REQUIRED_FIELD_BITMAP_IS_SET(index)	\
    (required_fields_bitmap[(index)/8] & (1UL<<((index)%8)))

ProtobufCMessage *
protobuf_c_message_unpack(const ProtobufCMessageDescriptor *desc,
              ProtobufCAllocator *allocator,
              size_t len, const uint8_t *data)
{
    ProtobufCMessage *rv;
    size_t rem = len;
    const uint8_t *at = data;
    const ProtobufCFieldDescriptor *last_field = desc->fields + 0;

    if (allocator == NULL)
        allocator = &protobuf_c__allocator;

    ScannedMember * first_member_slab = do_alloc(allocator, ( (1UL << FIRST_SCANNED_MEMBER_SLAB_SIZE_LOG2)*sizeof(ScannedMember) ) );
    if (!first_member_slab)
        return (NULL);

    memset(first_member_slab, 0, (1UL << FIRST_SCANNED_MEMBER_SLAB_SIZE_LOG2)*sizeof(ScannedMember) );
   
    /*
     * scanned_member_slabs[i] is an array of arrays of ScannedMember.
     * The first slab (scanned_member_slabs[0] is just a pointer to
     * first_member_slab), above. All subsequent slabs will be allocated
     * using the allocator.
     */
    ScannedMember **scanned_member_slabs = do_alloc(allocator, (MAX_SCANNED_MEMBER_SLAB + 1) * sizeof(ScannedMember *) );
    if(!scanned_member_slabs)
    {
        do_free(allocator, first_member_slab);
        return NULL;
    }

    memset(scanned_member_slabs, 0, (MAX_SCANNED_MEMBER_SLAB + 1) * sizeof(*scanned_member_slabs));


    unsigned which_slab = 0; /* the slab we are currently populating */
    unsigned in_slab_index = 0; /* number of members in the slab */
    size_t n_unknown = 0;
    unsigned f;
    unsigned j;
    unsigned i_slab;
    unsigned last_field_index = 0;
    unsigned required_fields_bitmap_len;
    unsigned char * required_fields_bitmap_stack = do_alloc(allocator, 16*sizeof(unsigned char) );
    if (!required_fields_bitmap_stack)
    {
        do_free(allocator, first_member_slab);
        do_free(allocator, scanned_member_slabs);
        return (NULL);
    }

    memset(required_fields_bitmap_stack, 0, 16*sizeof(unsigned char) );
    
    unsigned char *required_fields_bitmap = required_fields_bitmap_stack;
    protobuf_c_boolean required_fields_bitmap_alloced = FALSE;

    ASSERT_IS_MESSAGE_DESCRIPTOR(desc);

    rv = do_alloc(allocator, desc->sizeof_message);
    if (!rv)
    {
        do_free(allocator, required_fields_bitmap_stack);
        do_free(allocator, first_member_slab);
        do_free(allocator, scanned_member_slabs);

        return (NULL);
    }
    scanned_member_slabs[0] = first_member_slab;

    required_fields_bitmap_len = (desc->n_fields + 7) / 8;
    if (required_fields_bitmap_len > sizeof(required_fields_bitmap_stack)) {
        required_fields_bitmap = do_alloc(allocator, required_fields_bitmap_len);
        if (!required_fields_bitmap) {
            do_free(allocator, required_fields_bitmap_stack);
            do_free(allocator, first_member_slab);
            do_free(allocator, scanned_member_slabs);
            do_free(allocator, rv);
            return (NULL);
        }
        required_fields_bitmap_alloced = TRUE;
    }

    memset(required_fields_bitmap, 0, required_fields_bitmap_len);
    
    /*
     * Generated code always defines "message_init". However, we provide a
     * fallback for (1) users of old protobuf-c generated-code that do not
     * provide the function, and (2) descriptors constructed from some other
     * source (most likely, direct construction from the .proto file).
     */
    if (desc->message_init != NULL)
        protobuf_c_message_init(desc, rv);
    else
        message_init_generic(desc, rv);

    while (rem > 0) {
        uint32_t tag;
        ProtobufCWireType wire_type;
        size_t used = parse_tag_and_wiretype(rem, at, &tag, &wire_type);
        const ProtobufCFieldDescriptor *field;
        ScannedMember tmp;

        if (used == 0) {
            PROTOBUF_C_UNPACK_ERROR("error parsing tag/wiretype at offset %u",
                        (unsigned) (at - data));
            goto error_cleanup_during_scan;
        }
        /*
         * \todo Consider optimizing for field[1].id == tag, if field[1]
         * exists!
         */
        if (last_field == NULL || last_field->id != tag) {
            /* lookup field */
            int field_index =
                int_range_lookup(desc->n_field_ranges,
                         desc->field_ranges,
                         tag);
            if (field_index < 0) {
                field = NULL;
                n_unknown++;
            } else {
                field = desc->fields + field_index;
                last_field = field;
                last_field_index = field_index;
            }
        } else {
            field = last_field;
        }

        if (field != NULL && field->label == PROTOBUF_C_LABEL_REQUIRED)
            REQUIRED_FIELD_BITMAP_SET(last_field_index);

        at += used;
        rem -= used;
        tmp.tag = tag;
        tmp.wire_type = wire_type;
        tmp.field = field;
        tmp.data = at;
        tmp.length_prefix_len = 0;

        switch (wire_type) {
        case PROTOBUF_C_WIRE_TYPE_VARINT: {
            unsigned max_len = rem < 10 ? rem : 10;
            unsigned i;

            for (i = 0; i < max_len; i++)
                if ((at[i] & 0x80) == 0)
                    break;
            if (i == max_len) {
                PROTOBUF_C_UNPACK_ERROR("unterminated varint at offset %u",
                            (unsigned) (at - data));
                goto error_cleanup_during_scan;
            }
            tmp.len = i + 1;
            break;
        }
        case PROTOBUF_C_WIRE_TYPE_64BIT:
            if (rem < 8) {
                PROTOBUF_C_UNPACK_ERROR("too short after 64bit wiretype at offset %u",
                            (unsigned) (at - data));
                goto error_cleanup_during_scan;
            }
            tmp.len = 8;
            break;
        case PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED: {
            size_t pref_len;

            tmp.len = scan_length_prefixed_data(rem, at, &pref_len);
            if (tmp.len == 0) {
                /* NOTE: scan_length_prefixed_data calls UNPACK_ERROR */
                goto error_cleanup_during_scan;
            }
            tmp.length_prefix_len = pref_len;
            break;
        }
        case PROTOBUF_C_WIRE_TYPE_32BIT:
            if (rem < 4) {
                PROTOBUF_C_UNPACK_ERROR("too short after 32bit wiretype at offset %u",
                          (unsigned) (at - data));
                goto error_cleanup_during_scan;
            }
            tmp.len = 4;
            break;
        default:
            PROTOBUF_C_UNPACK_ERROR("unsupported tag %u at offset %u",
                        wire_type, (unsigned) (at - data));
            goto error_cleanup_during_scan;
        }

        if (in_slab_index == (1UL <<
            (which_slab + FIRST_SCANNED_MEMBER_SLAB_SIZE_LOG2)))
        {
            size_t size;

            in_slab_index = 0;
            if (which_slab == MAX_SCANNED_MEMBER_SLAB) {
                PROTOBUF_C_UNPACK_ERROR("too many fields");
                goto error_cleanup_during_scan;
            }
            which_slab++;
            size = sizeof(ScannedMember)
                << (which_slab + FIRST_SCANNED_MEMBER_SLAB_SIZE_LOG2);
            scanned_member_slabs[which_slab] = do_alloc(allocator, size);
            if (scanned_member_slabs[which_slab] == NULL)
                goto error_cleanup_during_scan;
        }
        scanned_member_slabs[which_slab][in_slab_index++] = tmp;

        if (field != NULL && field->label == PROTOBUF_C_LABEL_REPEATED) {
            size_t *n = STRUCT_MEMBER_PTR(size_t, rv,
                              field->quantifier_offset);
            if (wire_type == PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED &&
                (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED) ||
                 is_packable_type(field->type)))
            {
                size_t count;
                if (!count_packed_elements(field->type,
                               tmp.len -
                               tmp.length_prefix_len,
                               tmp.data +
                               tmp.length_prefix_len,
                               &count))
                {
                    PROTOBUF_C_UNPACK_ERROR("counting packed elements");
                    goto error_cleanup_during_scan;
                }
                *n += count;
            } else {
                *n += 1;
            }
        }

        at += tmp.len;
        rem -= tmp.len;
    }

    /* allocate space for repeated fields, also check that all required fields have been set */
    for (f = 0; f < desc->n_fields; f++) {
        const ProtobufCFieldDescriptor *field = desc->fields + f;
        if (field->label == PROTOBUF_C_LABEL_REPEATED) {
            size_t siz =
                sizeof_elt_in_repeated_array(field->type);
            size_t *n_ptr =
                STRUCT_MEMBER_PTR(size_t, rv,
                          field->quantifier_offset);
            if (*n_ptr != 0) {
                unsigned n = *n_ptr;
                void *a;
                *n_ptr = 0;
                assert(rv->descriptor != NULL);
#define CLEAR_REMAINING_N_PTRS()                                              \
              for(f++;f < desc->n_fields; f++)                                \
                {                                                             \
                  field = desc->fields + f;                                   \
                  if (field->label == PROTOBUF_C_LABEL_REPEATED)              \
                    STRUCT_MEMBER (size_t, rv, field->quantifier_offset) = 0; \
                }
                a = do_alloc(allocator, siz * n);
                if (!a) {
                    CLEAR_REMAINING_N_PTRS();
                    goto error_cleanup;
                }
                STRUCT_MEMBER(void *, rv, field->offset) = a;
            }
        } else if (field->label == PROTOBUF_C_LABEL_REQUIRED) {
            if (field->default_value == NULL &&
                !REQUIRED_FIELD_BITMAP_IS_SET(f))
            {
                CLEAR_REMAINING_N_PTRS();
                PROTOBUF_C_UNPACK_ERROR("message '%s': missing required field '%s'",
                            desc->name, field->name);
                goto error_cleanup;
            }
        }
    }
#undef CLEAR_REMAINING_N_PTRS

    /* allocate space for unknown fields */
    if (n_unknown) {
        rv->unknown_fields = do_alloc(allocator,
                          n_unknown * sizeof(ProtobufCMessageUnknownField));
        if (rv->unknown_fields == NULL)
            goto error_cleanup;
    }

    /* do real parsing */
    for (i_slab = 0; i_slab <= which_slab; i_slab++) {
        unsigned max = (i_slab == which_slab) ?
            in_slab_index : (1UL << (i_slab + 4));
        ScannedMember *slab = scanned_member_slabs[i_slab];

        for (j = 0; j < max; j++) {
            if (!parse_member(slab + j, rv, allocator)) {
                PROTOBUF_C_UNPACK_ERROR("error parsing member %s of %s",
                            slab->field ? slab->field->name : "*unknown-field*",
                    desc->name);
                goto error_cleanup;
            }
        }
    }

    /* cleanup */
    for (j = 1; j <= which_slab; j++)
        do_free(allocator, scanned_member_slabs[j]);
    if (required_fields_bitmap_alloced)
        do_free(allocator, required_fields_bitmap);
    do_free(allocator, required_fields_bitmap_stack);
    do_free(allocator, first_member_slab);
    do_free(allocator, scanned_member_slabs);
    return rv;

error_cleanup:
    protobuf_c_message_free_unpacked(rv, allocator);
    for (j = 1; j <= which_slab; j++)
        do_free(allocator, scanned_member_slabs[j]);
    if (required_fields_bitmap_alloced)
        do_free(allocator, required_fields_bitmap);
    do_free(allocator, required_fields_bitmap_stack);
    do_free(allocator, first_member_slab);
    do_free(allocator, scanned_member_slabs);
    return NULL;

error_cleanup_during_scan:
    do_free(allocator, rv);
    for (j = 1; j <= which_slab; j++)
        do_free(allocator, scanned_member_slabs[j]);
    if (required_fields_bitmap_alloced)
        do_free(allocator, required_fields_bitmap);
    do_free(allocator, required_fields_bitmap_stack);
    do_free(allocator, first_member_slab);
    do_free(allocator, scanned_member_slabs);
    return NULL;
}

void
protobuf_c_message_free_unpacked(ProtobufCMessage *message,
                 ProtobufCAllocator *allocator)
{
    const ProtobufCMessageDescriptor *desc;
    unsigned f;

    if (message == NULL)
        return;

    desc = message->descriptor;

    ASSERT_IS_MESSAGE(message);

    if (allocator == NULL)
        allocator = &protobuf_c__allocator;
    message->descriptor = NULL;
    for (f = 0; f < desc->n_fields; f++) {
        if (0 != (desc->fields[f].flags & PROTOBUF_C_FIELD_FLAG_ONEOF) &&
            desc->fields[f].id !=
            STRUCT_MEMBER(uint32_t, message, desc->fields[f].quantifier_offset))
        {
            /* This is not the selected oneof, skip it */
            continue;
        }

        if (desc->fields[f].label == PROTOBUF_C_LABEL_REPEATED) {
            size_t n = STRUCT_MEMBER(size_t,
                         message,
                         desc->fields[f].quantifier_offset);
            void *arr = STRUCT_MEMBER(void *,
                          message,
                          desc->fields[f].offset);

            if (arr != NULL) {
                if (desc->fields[f].type == PROTOBUF_C_TYPE_STRING) {
                    unsigned i;
                    for (i = 0; i < n; i++)
                        do_free(allocator, ((char **) arr)[i]);
                } else if (desc->fields[f].type == PROTOBUF_C_TYPE_BYTES) {
                    unsigned i;
                    for (i = 0; i < n; i++)
                        do_free(allocator, ((ProtobufCBinaryData *) arr)[i].data);
                } else if (desc->fields[f].type == PROTOBUF_C_TYPE_MESSAGE) {
                    unsigned i;
                    for (i = 0; i < n; i++)
                        protobuf_c_message_free_unpacked(
                            ((ProtobufCMessage **) arr)[i],
                            allocator
                        );
                }
                do_free(allocator, arr);
            }
        } else if (desc->fields[f].type == PROTOBUF_C_TYPE_STRING) {
            char *str = STRUCT_MEMBER(char *, message,
                          desc->fields[f].offset);

            if (str && str != desc->fields[f].default_value)
                do_free(allocator, str);
        } else if (desc->fields[f].type == PROTOBUF_C_TYPE_BYTES) {
            void *data = STRUCT_MEMBER(ProtobufCBinaryData, message,
                           desc->fields[f].offset).data;
            const ProtobufCBinaryData *default_bd;

            default_bd = desc->fields[f].default_value;
            if (data != NULL &&
                (default_bd == NULL ||
                 default_bd->data != data))
            {
                do_free(allocator, data);
            }
        } else if (desc->fields[f].type == PROTOBUF_C_TYPE_MESSAGE) {
            ProtobufCMessage *sm;

            sm = STRUCT_MEMBER(ProtobufCMessage *, message,
                       desc->fields[f].offset);
            if (sm && sm != desc->fields[f].default_value)
                protobuf_c_message_free_unpacked(sm, allocator);
        }
    }

    for (f = 0; f < message->n_unknown_fields; f++)
        do_free(allocator, message->unknown_fields[f].data);
    if (message->unknown_fields != NULL)
        do_free(allocator, message->unknown_fields);

    do_free(allocator, message);
}

void
protobuf_c_message_init(const ProtobufCMessageDescriptor * descriptor,
            void *message)
{
    descriptor->message_init((ProtobufCMessage *) (message));
}

protobuf_c_boolean
protobuf_c_message_check(const ProtobufCMessage *message)
{
    unsigned i;

    if (!message ||
        !message->descriptor ||
        message->descriptor->magic != PROTOBUF_C__MESSAGE_DESCRIPTOR_MAGIC)
    {
        return FALSE;
    }

    for (i = 0; i < message->descriptor->n_fields; i++) {
        const ProtobufCFieldDescriptor *f = message->descriptor->fields + i;
        ProtobufCType type = f->type;
        ProtobufCLabel label = f->label;
        void *field = STRUCT_MEMBER_P (message, f->offset);

        if (label == PROTOBUF_C_LABEL_REPEATED) {
            size_t *quantity = STRUCT_MEMBER_P (message, f->quantifier_offset);

            if (*quantity > 0 && *(void **) field == NULL) {
                return FALSE;
            }

            if (type == PROTOBUF_C_TYPE_MESSAGE) {
                ProtobufCMessage **submessage = *(ProtobufCMessage ***) field;
                unsigned j;
                for (j = 0; j < *quantity; j++) {
                    if (!protobuf_c_message_check(submessage[j]))
                        return FALSE;
                }
            } else if (type == PROTOBUF_C_TYPE_STRING) {
                char **string = *(char ***) field;
                unsigned j;
                for (j = 0; j < *quantity; j++) {
                    if (!string[j])
                        return FALSE;
                }
            } else if (type == PROTOBUF_C_TYPE_BYTES) {
                ProtobufCBinaryData *bd = *(ProtobufCBinaryData **) field;
                unsigned j;
                for (j = 0; j < *quantity; j++) {
                    if (bd[j].len > 0 && bd[j].data == NULL)
                        return FALSE;
                }
            }

        } else { /* PROTOBUF_C_LABEL_REQUIRED or PROTOBUF_C_LABEL_OPTIONAL */

            if (type == PROTOBUF_C_TYPE_MESSAGE) {
                ProtobufCMessage *submessage = *(ProtobufCMessage **) field;
                if (label == PROTOBUF_C_LABEL_REQUIRED || submessage != NULL) {
                    if (!protobuf_c_message_check(submessage))
                        return FALSE;
                }
            } else if (type == PROTOBUF_C_TYPE_STRING) {
                char *string = *(char **) field;
                if (label == PROTOBUF_C_LABEL_REQUIRED && string == NULL)
                    return FALSE;
            } else if (type == PROTOBUF_C_TYPE_BYTES) {
                protobuf_c_boolean *has = STRUCT_MEMBER_P (message, f->quantifier_offset);
                ProtobufCBinaryData *bd = field;
                if (label == PROTOBUF_C_LABEL_REQUIRED || *has == TRUE) {
                    if (bd->len > 0 && bd->data == NULL)
                        return FALSE;
                }
            }
        }
    }

    return TRUE;
}

/* === services === */

typedef void (*GenericHandler) (void *service,
                const ProtobufCMessage *input,
                ProtobufCClosure closure,
                void *closure_data);
void
protobuf_c_service_invoke_internal(ProtobufCService *service,
                   unsigned method_index,
                   const ProtobufCMessage *input,
                   ProtobufCClosure closure,
                   void *closure_data)
{
    GenericHandler *handlers;
    GenericHandler handler;

    /*
     * Verify that method_index is within range. If this fails, you are
     * likely invoking a newly added method on an old service. (Although
     * other memory corruption bugs can cause this assertion too.)
     */
    assert(method_index < service->descriptor->n_methods);

    /*
     * Get the array of virtual methods (which are enumerated by the
     * generated code).
     */
    handlers = (GenericHandler *) (service + 1);

    /*
     * Get our method and invoke it.
     * \todo Seems like handler == NULL is a situation that needs handling.
     */
    handler = handlers[method_index];
    (*handler)(service, input, closure, closure_data);
}

void
protobuf_c_service_generated_init(ProtobufCService *service,
                  const ProtobufCServiceDescriptor *descriptor,
                  ProtobufCServiceDestroy destroy)
{
    ASSERT_IS_SERVICE_DESCRIPTOR(descriptor);
    service->descriptor = descriptor;
    service->destroy = destroy;
    service->invoke = protobuf_c_service_invoke_internal;
    memset(service + 1, 0, descriptor->n_methods * sizeof(GenericHandler));
}

void protobuf_c_service_destroy(ProtobufCService *service)
{
    service->destroy(service);
}

/* --- querying the descriptors --- */

const ProtobufCEnumValue *
protobuf_c_enum_descriptor_get_value_by_name(const ProtobufCEnumDescriptor *desc,
                         const char *name)
{
    unsigned start = 0;
    unsigned count;

    if (desc == NULL || desc->values_by_name == NULL)
        return NULL;

    count = desc->n_value_names;

    while (count > 1) {
        unsigned mid = start + count / 2;
        int rv = strcmp(desc->values_by_name[mid].name, name);
        if (rv == 0)
            return desc->values + desc->values_by_name[mid].index;
        else if (rv < 0) {
            count = start + count - (mid + 1);
            start = mid + 1;
        } else
            count = mid - start;
    }
    if (count == 0)
        return NULL;
    if (strcmp(desc->values_by_name[start].name, name) == 0)
        return desc->values + desc->values_by_name[start].index;
    return NULL;
}

const ProtobufCEnumValue *
protobuf_c_enum_descriptor_get_value(const ProtobufCEnumDescriptor *desc,
                     int value)
{
    int rv = int_range_lookup(desc->n_value_ranges, desc->value_ranges, value);
    if (rv < 0)
        return NULL;
    return desc->values + rv;
}

const ProtobufCFieldDescriptor *
protobuf_c_message_descriptor_get_field_by_name(const ProtobufCMessageDescriptor *desc,
                        const char *name)
{
    unsigned start = 0;
    unsigned count;
    const ProtobufCFieldDescriptor *field;

    if (desc == NULL || desc->fields_sorted_by_name == NULL)
        return NULL;

    count = desc->n_fields;

    while (count > 1) {
        unsigned mid = start + count / 2;
        int rv;
        field = desc->fields + desc->fields_sorted_by_name[mid];
        rv = strcmp(field->name, name);
        if (rv == 0)
            return field;
        else if (rv < 0) {
            count = start + count - (mid + 1);
            start = mid + 1;
        } else
            count = mid - start;
    }
    if (count == 0)
        return NULL;
    field = desc->fields + desc->fields_sorted_by_name[start];
    if (strcmp(field->name, name) == 0)
        return field;
    return NULL;
}

const ProtobufCFieldDescriptor *
protobuf_c_message_descriptor_get_field(const ProtobufCMessageDescriptor *desc,
                    unsigned value)
{
    int rv = int_range_lookup(desc->n_field_ranges,desc->field_ranges, value);
    if (rv < 0)
        return NULL;
    return desc->fields + rv;
}

const ProtobufCMethodDescriptor *
protobuf_c_service_descriptor_get_method_by_name(const ProtobufCServiceDescriptor *desc,
                         const char *name)
{
    unsigned start = 0;
    unsigned count;

    if (desc == NULL || desc->method_indices_by_name == NULL)
        return NULL;

    count = desc->n_methods;

    while (count > 1) {
        unsigned mid = start + count / 2;
        unsigned mid_index = desc->method_indices_by_name[mid];
        const char *mid_name = desc->methods[mid_index].name;
        int rv = strcmp(mid_name, name);

        if (rv == 0)
            return desc->methods + desc->method_indices_by_name[mid];
        if (rv < 0) {
            count = start + count - (mid + 1);
            start = mid + 1;
        } else {
            count = mid - start;
        }
    }
    if (count == 0)
        return NULL;
    if (strcmp(desc->methods[desc->method_indices_by_name[start]].name, name) == 0)
        return desc->methods + desc->method_indices_by_name[start];
    return NULL;
}
